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.

    €3.00 at the iDoc store
  • Flat Picks

    Flat Picks

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

    €3.00 at the iDoc store
  • Hard Plastic Picks

    Hard Plastic Picks

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

    €3.00 at the iDoc store
  • 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 €14.47 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.

    €8.00 at the iDoc store
  • 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.

    €9.00 at the iDoc store
  • iPlastix

    iPlastix

    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.

    €9.00 at the iDoc store
  • Plastic prying tool

    Plastic prying tool

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

    €3.00 at the iDoc store
  • Suction cup

    Suction cup

    A suction cup is perfect for lifting smooth surfaces such as displays or rear glass panels.

    €3.00 at the iDoc store
  • Phillips PH00 screwdriver

    Phillips PH00 screwdriver

    You need the right screwdriver for removing PH00 screws.

    €11.00 at the iDoc store

Required replacement part

Show all replacement parts for the Galaxy S21 5G 

Replacement parts and tools for this repair

Our tools plus the right spare part help you fix your device easily.

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

    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
  4. Detaching the back cover

    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
  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 NFC antenna

    • 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 NFC antenna's cover plate.
    2. Then put them on your 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
    • 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. Detaching the NFC antenna's connector

    Galaxy S21 5G - Detaching the NFC antenna's connector 01
    Galaxy S21 5G - Detaching the NFC antenna's connector 02
    Galaxy S21 5G - Detaching the NFC antenna's connector 03
    Used tools
    • Connector
    1. Then separate the black connector of the NFC antenna by carefully levering it off the circuit board with a spudger as well.
    Used tools
  9. Removing the NFC antenna

    Galaxy S21 5G - Removing the NFC antenna 01
    Galaxy S21 5G - Removing the NFC antenna 02
    Galaxy S21 5G - Removing the NFC antenna 03

    The lower end of the NFC antenna is slightly glued.

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

    • 6 × 4.9 mm Phillips
    1. Remove the six Phillips screws from the speaker module.
    2. Then place them on the 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

    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
  12. Removing the connecting cables

    • 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
  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
    • 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

    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
  18. Detaching the battery

    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
  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

    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
  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

    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
  25. Screwing the speaker tight

    • 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.
  26. Inserting the NFC antenna

    Galaxy S21 5G - Inserting the NFC antenna  01
    Galaxy S21 5G - Inserting the NFC antenna  02
    1. Reposition the NFC antenna in the screen unit and press its back end slightly to allow the glue to bond again.
  27. Attaching the NFC antenna's connector

    Galaxy S21 5G - Attaching the NFC antenna's connector 01
    Galaxy S21 5G - Attaching the NFC antenna's connector 02
    Galaxy S21 5G - Attaching the NFC antenna's connector 03
    • Connector
    1. Lift up the metal cover of the NFC antenna to attach the black connector of the NFC antenna 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 NFC antenna tight

    • 5 × 4.9 mm Phillips
    1. Once the battery and NFC antenna connectors are reconnected, you can screw the metal cover back on.
  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

    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
  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.
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