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

If the 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.

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.

    €2.00 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.

    €4.00 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.

    €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.

    €2.00 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.

    €13.00 at the iDoc store

Required replacement part

Show all replacement parts for the Galaxy S21 FE 5G 

Passendes Werkzeug

Mit unserem Werkzeug gelingt dir die Reparatur.

for €59.00

Getting started with the repair of your Galaxy S21 FE 5G

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

21 steps
  1. Switching off your Samsung Galaxy S21 FE 5G

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

    Use our checklist to test the basic functions of your Galaxy S21 FE 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. You can also switch off your Galaxy via quick access.
    2. Tap on Power off in the displayed menu.
  2. Heating up the back cover

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

    Once you open your device its specified IP68 certification will expire.

    The edge of the back cover is heavily glued. In order to remove it, you first have to heat the adhesive sufficiently with hot air. Use a heat gun or an ordinary hair dryer for this purpose.
    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

    As an alternative to the suction cup, we can recommend the iSclack, which requires less force to lift up the back cover.

    The iFlex can be inserted particularly well between the back cover and the screen unit due to its sharp edges.

    1. Attach a suction cup to the lower edge of the back cover and pull it upwards to create a narrow gap.
    2. At the same time, insert a flat tool into the gap between the back cover and the screen unit.


    Used tools
  4. Detaching the back cover

    Galaxy S21 FE 5G - Detaching the back cover 01
    Galaxy S21 FE 5G - Detaching the back cover 02
    Galaxy S21 FE 5G - Detaching the back cover 03
    Galaxy S21 FE 5G - Detaching the back cover 04
    Used tools
    Heat gun

    To avoid damaging the camera module, you should not insert your tool too far.

    In order to prevent the glue of the back cover from bonding again, we recommend sliding flat plastic picks under the back cover at regular intervals.

    1. Drive your tool completely around the edge of the back cover to loosen it piece by piece.
    2. Put the detached back cover aside.


    Used tools
  5. Detaching the board cover

    • 9 × 3.8 mm Phillips

    We recommend using a screw storage to keep all disassembled parts and screws safe and organized. Our magnetic pad has the additional advantage that nothing can move on it.

    A small arrow as well as a notch show you where you can place your levering tool best.

    1. Loosen the nine Phillips screws that secure the plastic cover above the motherboard.
    2. Then carefully lever the cover out of its guide with a spudger.
  6. Disconnecting battery and charging coil

    Galaxy S21 FE 5G - Disconnecting battery and charging coil 01
    Galaxy S21 FE 5G - Disconnecting battery and charging coil 02
    Galaxy S21 FE 5G - Disconnecting battery and charging coil 03
    Galaxy S21 FE 5G - Disconnecting battery and charging coil 04
    Galaxy S21 FE 5G - Disconnecting battery and charging coil 05
    Used tools
    • Connector

    To avoid a potential short circuit during the repair, you should always detach the battery connector first.

    When separating connectors, always start from the side where there are no small components on the board. This way you avoid potential damage.
    1. Fold the loosened board cover around.
    2. Carefully disconnect the orange battery connector and black charging coil connector with a spudger from the motherboard.
    3. Pull the glued end of the cover off the speaker.
    Used tools
  7. Removing the speaker

    • 6 × 3.8 mm Phillips
    1. Loosen the six Phillips screws that hold the speaker in place.
    2. Carefully lever the speaker out of its guide and set it aside.
  8. Separating the screen cable

    • Connector

    The screen cable of the S21 FE 5G can be fully removed. The lower part of the cable is connected to a separate slot that sits somewhat recessed in the screen unit.

    1. Carefully separate the two connectors of the screen cable with a spudger.
    2. Take the disconnected cable out of your device.
    Used tools
  9. Separating the connecting cables

    • Connector
    1. Separate the two connecting cables from the motherboard and the USB board with a spudger.
    2. Put the disconnected cables aside.
    Used tools
  10. Heating up the battery's adhesive

    Galaxy S21 FE 5G - Heating up the battery's adhesive 01
    Used tools
    Heat gun

    The battery of the S21 FE 5G is heavily glued into the display unit. In order to loosen it safely, you need to heat up the glue in advance.

    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 area on the screen.
    Used tools
  11. 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
  12. Removing the battery

    Galaxy S21 FE 5G - Removing the battery 01
    Galaxy S21 FE 5G - Removing the battery 02
    Galaxy S21 FE 5G - Removing the battery 03
    Galaxy S21 FE 5G - Removing the battery 04
    Galaxy S21 FE 5G - Removing the battery 05

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

    1. Place a battery spudger on the lower edge of the battery and carefully lift it upwards.
    2. Remove the detached battery from the device.
    3. Insert the flat iPlastix under the battery at the lifted edge and detach the battery bit by bit from the bottom of the screen unit.
    Used tools
  13. Preparing the new battery

    Galaxy S21 FE 5G - Preparing the new battery 01
    Galaxy S21 FE 5G - Preparing the new battery 02
    Verwendete Ersatzteile
    Samsung Galaxy S21 FE 5G battery
    1. If necessary, bend the battery connector, so that it can be pressed well onto the slot on the motherboard.
    2. Remove the protective films from the front and back of the battery.
    Verwendete Ersatzteile
    Samsung Galaxy S21 FE 5G battery
  14. Inserting the replacement battery

    Galaxy S21 FE 5G - Inserting the replacement battery 01
    Galaxy S21 FE 5G - Inserting the replacement battery 02
    1. Put the replacement battery back into its guide and press it firmly.
  15. Attaching the connecting cables

    • Connector

    The cable labeling will help you align them in the device.

    Never attach connectors by force. Damage can lead to the failure of an entire component.

    1. Align the two connecting cables one after the other in the device and attach their two connectors on the USB and motherboard each.
    Used tools
  16. Attaching the screen cable

    • Connector

    The cable labeling will help you align it in the device.

    1. Align the screen cable in the device and attach its two connectors on the motherboard and the separate slot in the screen unit.
    Used tools
  17. Installing the speaker

    • 6 × 3.8 mm Phillips
    Make sure that the speaker sits level all over. Its plastic lugs must fit into the edge of the case.
    1. Put the speaker back in its original position.
    2. Screw it in place with the six Phillips screws.
  18. Connecting battery and charging coil

    Galaxy S21 FE 5G - Connecting battery and charging coil 01
    Galaxy S21 FE 5G - Connecting battery and charging coil 02
    Galaxy S21 FE 5G - Connecting battery and charging coil 03
    Galaxy S21 FE 5G - Connecting battery and charging coil 04
    • Connector


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

    1. Align the charging coil above your device.
    2. Connect the black charging coil connector and the orange battery connector to the motherboard.
  19. Installing the board cover

    • 9 × 3.8 mm Phillips
    1. Place the board cover in its guide. It must sit level all over.
    2. Reattach its glued end to the speaker.
    3. Screw the cover in place with the nine Phillips screws.
  20. Testing the replacement battery

    Galaxy S21 FE 5G - Testing the replacement battery 01
    Galaxy S21 FE 5G - Testing the replacement battery 02
    Galaxy S21 FE 5G - Testing the replacement battery 03

    Before you close your iPhone 13 for good, we recommend testing the replacement screen as well as other basic functions of your phone. Again, use our checklist for this or the internal Samsung test menu, which you call up via the code *#0*#.

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

    1. Connect your Galaxy to the mains in order to see if the replacement battery is charging.
    2. Also place it on a wireless charger, if available, to check the wireless charging function.
  21. Attaching a new adhesive frame (optional)

    If the adhesive frame 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 use a new adhesive frame. On our YouTube channel you can find a detailed video on the topic.

    1. Peel off the carrier film from the bottom of the adhesive frame and press it onto the edge of the back cover. A spudger can help you with this.
    2. Now carefully peel off the remaining protective film from the top of the adhesive frame.
    Used tools
    Verwendete Ersatzteile
  22. Attaching the back cover

    Galaxy S21 FE 5G - Attaching the back cover 01
    Galaxy S21 FE 5G - Attaching the back cover 02
    Used tools
    Heat gun

    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.

    1. Close your Galaxy S21 FE 5G after the repair by pressing the back cover back onto the screen unit.
    Used tools
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