The battery of your Galaxy S21 5G discharges way to fast? Do you notice a significant drop in performance?

If the one-year manufacturers' warranty has already expired, it is recommended that you replace the battery. In this detailed photo tutorial, we will show you step by step how to do it.

Once you open your device, the specified IP certification (protection against dust and water ingress) will expire. If your battery is inflated, keep in mind that the gas inside the battery is flammable and can escape. If you do not feel confident enough, have it replaced at a repair shop.

To avoid scratches on case and screen glass, make sure your workspace is clean and level.

We wish you good luck with your repair!

Required tools

  • Tool for prying out batteries

    Tool for prying out batteries

    You have to use a very stable tool to pry out the battery. At the same time, it has to be flat enough to insert below the battery.

    from €10.99 on Amazon
  • Flat Picks

    Flat Picks

    You need a very flat tool such as a flat pick to pry out parts that are glued in place.

    from €11.95 on Amazon
  • Heat gun

    Heat gun

    You can use a heat gun to heat parts that are glued on so they’re easier to remove. In most cases, you can also use a hairdryer.

    from €15.99 on Amazon
  • iFlex Opening Tool

    iFlex Opening Tool

    Opening your smartphone can be a very delicate operation, especially if the glue is very persistent. The blade of the flexible but sturdy iFlex measures just 0.15 mm, so it fits in even the smallest gaps, such as between the screen and the frame. The practical iFlex is made of stainless steel and sits comfortably in the hand. This makes it the perfect assistant for every smartphone repair.

    from €10.95 on Amazon
  • iPlastix Opening Tool

    iPlastix Opening Tool

    Do you want to open your smartphone or lever out large parts like the battery? Then the iPlastix with its large blade will help you. The practical assistant is made of flexible, especially sturdy plastic and lies comfortably in the hand. Thanks to its design, you can even get into smaller gaps, for example to lift the screen or to prevent it from sticking together again.

    on Amazon
  • For storing screws

    For storing screws

    We recommend storing your screws so you don’t mix up the various screws and small parts.

    from €10.99 on Amazon
  • Pick Set

    Pick Set

    You need a flat but stable tool such as a pick to pry out parts that are glued in place.

    from €14.99 on Amazon
  • Plastic prying tool

    Plastic prying tool

    You need a flat plastic prying tool to disconnect the various plugs and connectors.

    from €14.99 on Amazon
  • Phillips PH00 screwdriver

    Phillips PH00 screwdriver

    You need the right screwdriver for removing PH00 screws.

    from €10.84 on Amazon

Required replacement part

  • Samsung Galaxy S21 5G Battery

    Samsung Galaxy S21 5G Battery

    on Amazon
Show all replacement parts for the Galaxy S21 5G 

Getting started with the repair of your Galaxy S21 5G

If you get stuck or have questions, you can post a comment. We’d be happy to help.

31 steps
  1. Switching off your Samsung Galaxy S21 5G

    Galaxy S21 5G - Switching off your Samsung Galaxy S21 5G 01
    Galaxy S21 5G - Switching off your Samsung Galaxy S21 5G 02
    Galaxy S21 5G - Switching off your Samsung Galaxy S21 5G 03

    Use our checklist to test the basic functions of your Galaxy S21 5G before repairing. This way you can check afterwards if your repair was successful.

    1. Press and hold the side and volume down button simultaneously for a few seconds.
    2. Tap Power off in the displayed menu and confirm with your unlock code.
  2. Heating up the back cover

    Galaxy S21 5G - Heating up the back cover 01
    Galaxy S21 5G - Heating up the back cover 02
    Used tools
    Heat gun

    The edge of the back cover is heavily glued. It is therefore essential to first heat it up sufficiently. Use a hot air device for this purpose, such as a heat gun or an ordinary hair dryer.

    Be careful not to burn your fingers after heating. It is best to heat the back cover only to the point where you can still touch it.
    1. Heat the edge of the back cover by running the hot air device evenly over it.
    Used tools
  3. Lifting up the back cover

    Galaxy S21 5G - Lifting up the back cover 01
    Galaxy S21 5G - Lifting up the back cover 02
    Galaxy S21 5G - Lifting up the back cover 03
    Used tools
    iFlex Opening Tool
    VAKUPLASTIC Suction Cup

    To create a narrow gap between back cover and display unit you need a flat, stable tool. We recommend the iFlex for this, since it has particularly sharp edges that can be easily inserted.

    1. Attach a suction cup to the lower edge of the back cover and pull it upwards. Insert the iFlex between the display unit and the back cover at the same time.
    Used tools
    iFlex Opening Tool
    VAKUPLASTIC Suction Cup
  4. Detaching the back cover

    Galaxy S21 5G - Detaching the back cover 01
    Galaxy S21 5G - Detaching the back cover 02
    Galaxy S21 5G - Detaching the back cover 03
    Galaxy S21 5G - Detaching the back cover 04
    Used tools
    Heat gun
    Pick Set
    Flat Picks
    iPlastix Opening Tool
    VAKUPLASTIC Suction Cup

    To avoid damaging the edge of the case with the sharp edges of the iFlex, you should switch to a plastic tool like the iPlastix as soon as possible.

    To avoid damaging the camera module, you should not insert your tool too far into the device. We recommend the hard plastic pick at this point. Due to its shape it cannot be inserted too deeply.

    1. Drive the tool completely around the edge of the back cover to loosen it piece by piece.
    2. Slide flat picks under the back cover at regular intervals, so that the glue cannot bond again.


    Used tools
    iPlastix Opening Tool
    VAKUPLASTIC Suction Cup
  5. Removing the back cover

    Galaxy S21 5G - Removing the back cover 01
    Galaxy S21 5G - Removing the back cover 02
    Galaxy S21 5G - Removing the back cover 03
    1. Once the back cover is completely detached, you first have to remove all plastic picks.
    2. Then unfold it and put it aside.
  6. Unscrewing the charging coil cover

    Galaxy S21 5G - Unscrewing the charging coil cover 01
    Galaxy S21 5G - Unscrewing the charging coil cover 02
    Used tools
    Wiha PicoFinish Phillips Screwdriver PH00
    Magnetic Pad
    • 5 × 4.9 mm Phillips

    Use a screw storage to keep an overview during the repair and avoid losing anything. Use an old sewing box, for example. With our high-quality magnetic pad, you have the additional advantage that nothing slips.

    1. Loosen the five Phillips screws from the charging coil cover.
    2. Then put them on your magnetic pad.
    Used tools
    Wiha PicoFinish Phillips Screwdriver PH00
    Magnetic Pad
  7. Detaching the battery connector

    Galaxy S21 5G - Detaching the battery connector 01
    Galaxy S21 5G - Detaching the battery connector 02
    Galaxy S21 5G - Detaching the battery connector 03
    Used tools
    Pry Tool
    • Connector

    Always detach the battery connector as soon as possible to avoid a potential short circuit.

    When separating connectors, always start from the side where there are no small components on the motherboard. This way you avoid potential damage.

    1. Lift up the metal cover of the NFC antenna.
    2. Carefully pry the orange battery connector underneath from the motherboard with a plastic lever tool. We use a plastic spudger for this.
    Used tools
  8. Disconnecting the charging coil

    Galaxy S21 5G - Disconnecting the charging coil 01
    Galaxy S21 5G - Disconnecting the charging coil 02
    Galaxy S21 5G - Disconnecting the charging coil 03
    Used tools
    Pry Tool
    • Connector
    1. Then separate the black connector of the charging coil by carefully levering it off the circuit board with a spudger as well.
    Used tools
  9. Removing the charging coil

    Galaxy S21 5G - Removing the charging coil 01
    Galaxy S21 5G - Removing the charging coil 02
    Galaxy S21 5G - Removing the charging coil 03

    The lower end of the charging coil is slightly glued.

    1. Once the connectors are separated, you can carefully pull off the charging coil.
  10. Unscrewing the speaker

    Galaxy S21 5G - Unscrewing the speaker 01
    Galaxy S21 5G - Unscrewing the speaker 02
    Used tools
    Wiha PicoFinish Phillips Screwdriver PH00
    Magnetic Pad
    • 6 × 4.9 mm Phillips
    1. Remove the six Phillips screws from the speaker module.
    2. Then place them on the magnetic pad.
    Used tools
    Wiha PicoFinish Phillips Screwdriver PH00
    Magnetic Pad
  11. Removing the speaker

    Galaxy S21 5G - Removing the speaker 01
    Galaxy S21 5G - Removing the speaker 02
    Galaxy S21 5G - Removing the speaker 03
    Used tools
    Piergiacomi Tweezers 2a SA ESD

    A small arrow in the upper left corner shows you where to place your tool.

    1. Carefully lever the speaker module out of its guide and put it aside.
    Used tools
    Piergiacomi Tweezers 2a SA ESD
  12. Removing the connecting cables

    Galaxy S21 5G - Removing the connecting cables 01
    Galaxy S21 5G - Removing the connecting cables 02
    Galaxy S21 5G - Removing the connecting cables 03
    Galaxy S21 5G - Removing the connecting cables 04
    Used tools
    Piergiacomi Tweezers 2a SA ESD
    • Connector
    1. Separate the connectors of the two connecting cables from the USB and motherboard each.
    2. Then remove the detached cables from your device.
    Used tools
    Piergiacomi Tweezers 2a SA ESD
  13. Detaching the screen cable

    Galaxy S21 5G - Detaching the screen cable 01
    Galaxy S21 5G - Detaching the screen cable 02
    Galaxy S21 5G - Detaching the screen cable 03
    Used tools
    Pry Tool
    • Connector

    The screen cable is attached to a separate slot for the first time in the Galaxy S21, so it can be removed completely.

    1. Use a spudger to carefully lever the connectors of the screen cable off the USB and motherboard respectively.
    Used tools
  14. Removing the screen cable

    Galaxy S21 5G - Removing the screen cable 01
    Galaxy S21 5G - Removing the screen cable 02
    1. Remove the detached display cable from the device.
  15. Heating up the battery adhesive

    Galaxy S21 5G - Heating up the battery adhesive 01
    Galaxy S21 5G - Heating up the battery adhesive 02
    Used tools
    Heat gun

    The battery of the S21 5G is heavily glued into the display unit. In order to make it easier to remove, you should therefore heat it previously.

    Never heat the sensitive battery directly, but only from the display side.

    1. Heat the battery by running a hot air gun evenly over the corresponding opposite spot on the display.
    Used tools
  16. The right tools for your repair

    With the right tools, you will succeed in any repair. In our store you will find a large selection of professional quality tools.
    VIEW NOW
  17. Lifting up the battery

    Galaxy S21 5G - Lifting up the battery 01
    Galaxy S21 5G - Lifting up the battery 02
    Galaxy S21 5G - Lifting up the battery 03
    Used tools
    Battery Spudger
    VAKUPLASTIC Suction Cup

    Once the adhesive has warmed up sufficiently, the easiest way to lift the battery is to use a suction cup and a plastic lever tool.

    1. Place the suction cup on the lower edge of the battery and pull it upwards to lift the battery up.
    2. At the same time, use a plastic lever tool on the lower edge of the battery to push the battery upwards. We use the battery spudger for this purpose.
    Used tools
    Battery Spudger
    VAKUPLASTIC Suction Cup
  18. Detaching the battery

    Galaxy S21 5G - Detaching the battery 01
    Galaxy S21 5G - Detaching the battery 02
    Galaxy S21 5G - Detaching the battery 03
    Galaxy S21 5G - Detaching the battery 04
    Used tools
    Flat Picks
    iPlastix Opening Tool
    VAKUPLASTIC Suction Cup

    The battery can be loosened particularly well if you move the iPlastix under the battery with a knife movement.

    You can insert a flat pick to prevent the adhesive from bonding again at a point that has already been loosened.

    1. Insert the flat iPlastix at the lifted edge and slide it under the battery bit by bit to completely detach it from the bottom of the screen unit.
    Used tools
    iPlastix Opening Tool
    VAKUPLASTIC Suction Cup
  19. Removing the battery

    Galaxy S21 5G - Removing the battery 01
    Galaxy S21 5G - Removing the battery 02
    1. Take the detached battery out of the device and put it aside.
  20. Preparing the new battery

    Galaxy S21 5G - Preparing the new battery 01
    Galaxy S21 5G - Preparing the new battery 02
    Galaxy S21 5G - Preparing the new battery 03
    Verwendete Ersatzteile
    Samsung Galaxy S21 5G Battery

    You may have to bend the connector of the replacement battery to ensure that it can be properly attached. Align it with the help of the connector slot of on the motherboard.

    1. Carefully bend the connector of the replacement battery before installing it.
    2. Then remove the protective foils from the battery's front and back.
    Verwendete Ersatzteile
    Samsung Galaxy S21 5G Battery
  21. Inserting the new battery

    Galaxy S21 5G - Inserting the new battery 01
    Galaxy S21 5G - Inserting the new battery 02
    1. Insert the replacement battery into the display unit and press it firmly.
  22. Attaching the screen cable

    Galaxy S21 5G - Attaching the screen cable 01
    Galaxy S21 5G - Attaching the screen cable 02
    Galaxy S21 5G - Attaching the screen cable 03
    Galaxy S21 5G - Attaching the screen cable 04
    • Connector

    The label on the screen cable will help you to align it.

    Never attach connectors by force. Damage can lead to the failure of an entire component.
    1. Align the display cable and press the two connectors respectively onto the motherboard and the separate slot. You should hear and feel them click into place.
  23. Attaching the connecting cables

    Galaxy S21 5G - Attaching the connecting cables 01
    Galaxy S21 5G - Attaching the connecting cables 02
    Galaxy S21 5G - Attaching the connecting cables 03
    Galaxy S21 5G - Attaching the connecting cables 04
    • Connector

    The label on the screen cable will help you to align it.

    1. Position the two connecting cables in the device again.
    2. Attach their two connectors to the motherboard and USB board respectively.


  24. Inserting the speaker

    Galaxy S21 5G - Inserting the speaker 01
    Galaxy S21 5G - Inserting the speaker 02
    Galaxy S21 5G - Inserting the speaker 03
    Verwendete Ersatzteile
    Samsung Galaxy S21 5G Loudspeaker

    The speaker module has three small lugs. To ensure that the module sits evenly in the device, these must be hooked into the frame of the screen unit when inserting it.

    1. Put the speaker back in its original position.
    Verwendete Ersatzteile
    Samsung Galaxy S21 5G Loudspeaker
  25. Screwing the speaker tight

    Galaxy S21 5G - Screwing the speaker tight 01
    Galaxy S21 5G - Screwing the speaker tight 02
    Used tools
    Wiha PicoFinish Phillips Screwdriver PH00
    • 6 × 4.9 mm Phillips

    When screwing components into place, make sure that you do not mix up the screws. A too long screw in the wrong place could damage the display in the worst case.

    1. Screw the speaker module in place with the six Phillips screws.
    Used tools
    Wiha PicoFinish Phillips Screwdriver PH00
  26. Installing the charging coil

    Galaxy S21 5G - Installing the charging coil 01
    Galaxy S21 5G - Installing the charging coil 02
    1. Reposition the NFC antenna in the screen unit and press its back end slightly to allow the glue to bond again.
  27. Connecting the charging coil

    Galaxy S21 5G - Connecting the charging coil 01
    Galaxy S21 5G - Connecting the charging coil 02
    Galaxy S21 5G - Connecting the charging coil 03
    • Connector
    1. Lift up the metal cover of the charging coil to attach its black connector that is located underneath.
  28. Attaching the battery connector

    Galaxy S21 5G - Attaching the battery connector 01
    Galaxy S21 5G - Attaching the battery connector 02
    Galaxy S21 5G - Attaching the battery connector 03

    Always connect the battery connector last to avoid a potential short circuit.

    1. You can now also reattach the orange battery connector to the motherboard.
  29. Screwing the cover plate in place

    Galaxy S21 5G - Screwing the cover plate in place 01
    Galaxy S21 5G - Screwing the cover plate in place 02
    Used tools
    Wiha PicoFinish Phillips Screwdriver PH00
    • 5 × 4.9 mm Phillips
    1. Once the battery and charging coil are reconnected, you can screw the metal cover back on.
    Used tools
    Wiha PicoFinish Phillips Screwdriver PH00
  30. Testing your Galaxy S21 5G

    Galaxy S21 5G - Testing your Galaxy S21 5G 01
    Galaxy S21 5G - Testing your Galaxy S21 5G 02
    Galaxy S21 5G - Testing your Galaxy S21 5G 03
    Galaxy S21 5G - Testing your Galaxy S21 5G 04

    If something doesn't work properly during testing, double-check that everything is installed and attached correctly.

    1. Connect your Galaxy to the mains in order to check the functionality of the replacement battery.
    2. Also place it on a wireless charger, if available, to check the wireless charging function.
    3. Call up the Samsung test menu via *#0*# in the phone app to test additional components. As an alternative use our checklist.
  31. Attaching a new adhesive frame (optional)

    Galaxy S21 5G - Attaching a new adhesive frame (optional) 01
    Galaxy S21 5G - Attaching a new adhesive frame (optional) 02
    Galaxy S21 5G - Attaching a new adhesive frame (optional) 03
    Galaxy S21 5G - Attaching a new adhesive frame (optional) 04
    Galaxy S21 5G - Attaching a new adhesive frame (optional) 05
    Used tools
    Pry Tool
    Verwendete Ersatzteile
    Samsung Galaxy S21 5G Adhesive Frame for Backcover

    Attaching a new adhesive frame is optional. If it is still in good condition, you do not need to install a new one. However, if it has defects or no longer sticks properly, we recommend that you install a new adhesive frame.

    1. We show you how to apply a new adhesive frame in detail in our YouTube video.
    Used tools
    Verwendete Ersatzteile
    Samsung Galaxy S21 5G Adhesive Frame for Backcover
  32. Attaching the back cover

    Galaxy S21 5G - Attaching the back cover 01
    Galaxy S21 5G - Attaching the back cover 02
    Galaxy S21 5G - Attaching the back cover 03
    Galaxy S21 5G - Attaching the back cover 04

    We recommend that you run hot air over the edge of the back cover again, so that the glue bonds properly. You can also weigh down your device with books for a few minutes or clamp it like in our example.

    1. Close your Galaxy S21 5G after the repair by pressing the back cover back onto the display unit.
Ø 5 (2 Ratings)

Bewerte unsere Anleitung

Hat dir unsere Anleitung weitergeholfen? Wir sind auf deine Beurteilung gespannt.

Submit rating

Submit rating

How did you like this repair guide?

Exceptional

Similar guides

You might also be interested in these guides.

You might be interested in

Get in touch with iDoc

Please contact our customer service for any questions about iDoc's products and services.

  • Send a message

    If you have a question about a guide or want to give us general feedback, just use our contact form

    Write a message
  • Free shipping

    From a minimum order value of 79.00 € your order will be shipped free of charge within Germany.

  • Call iDoc

    If you have any questions about our guides or services, call us from Monday to Friday, 10:00 a.m. to 6:00 p.m.

    +49 30 200 514 455
  • 5 star service

    We offer top quality and service. Our customers confirm this as well.

    Show reviews

Profi-Insights & Tipps für deine erfolgreiche Handy-Reparatur

iDoc schenkt dir den ultimativen Reparatur-Guide GUIDE GRATIS ANFORDERN

Profi-Insights & Tipps für deine erfolgreiche Handy-Reparatur

iDoc schenkt dir den ultimativen Reparatur-Guide GUIDE GRATIS ANFORDERN