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Samsung Galaxy S21 Logic Board Repair

Logic Board Repair guide for the Samsung Galaxy S21

Expert
~39 min
19 steps

Before you begin

Tools

  • Phillips #00 screwdriver
  • Plastic prying tools
  • Spudger tool
  • Suction cup tool
  • Heat gun or hair dryer
  • Tweezers
  • SIM eject tool

Parts / materials

  • Isopropyl alcohol (91%+)
  • Replacement back cover adhesive seal
  • Microfiber cleaning cloth

Safety

  • Disconnect the battery immediately after exposing the interior to prevent shorting components.
  • Wear safety glasses when applying heat to glass panels to protect against accidental cracking.
  • Do not bend or puncture the battery while working near motherboard connectors.
  • Wear an anti-static wrist strap to protect sensitive integrated circuits from ESD.

Overview

# Samsung Galaxy S21 Logic Board Repair Repair Guide Action-specific logic board repair walkthrough for the Samsung Galaxy S21. About 39 minutes across 19 steps. This DIY guide walks through logic board repair on the Samsung Galaxy S21 (Galaxy S series phone). Before you open the device, confirm the exact model number on the Samsung settings screen or rear housing so your replacement part matches the Galaxy S21 specifically—not a similar Galaxy S sibling. Most DIY techs finish this Samsung Galaxy S21 logic board repair in about 39 minutes when parts and tools are ready. Difficulty is rated expert for this model. Recommended tools for this Samsung Galaxy S21 job: Phillips #00 screwdriver, Plastic prying tools, Spudger tool, Suction cup tool, Heat gun or hair dryer, Tweezers, SIM eject tool. Parts and supplies: Isopropyl alcohol (91%+), Replacement back cover adhesive seal, Microfiber cleaning cloth. Power the Galaxy S21 off completely, remove SIMs/SD cards if present, and work on a clean, well-lit surface with a magnetic mat for screws. If a step feels wrong for your Samsung Galaxy S21, stop and compare the connector layout to the photos in this guide. When you prefer a same-day pro repair in Seattle instead, LML Repair can handle logic board repair for this model with tested parts and a workmanship warranty.

Step-by-step

  1. 1

    Eject the SIM tray

    1 min

    Insert a SIM eject tool or paperclip into the hole next to the SIM tray on the bottom of the phone. Push firmly to pop the tray out and remove it.

  2. 2

    Heat the rear panel

    3 min

    Use a heat gun or hair dryer to apply mild heat around the edges of the back cover for about two minutes. This softens the adhesive securing the rear panel.

  3. 3

    Apply a suction cup

    2 min

    Press a suction cup onto the lower portion of the back cover near the bottom edge. Pull up gently to create a small gap between the glass and the frame.

  4. 4

    Slice the rear adhesive

    4 min

    Insert a plastic prying tool or pick into the seam created by the suction cup. Carefully slide it around all four edges to slice through the adhesive.

  5. 5

    Remove the rear cover

    1 min

    Lift the rear cover straight off the chassis once all adhesive is severed. Set it aside on a clean surface.

  6. 6

    Unscrew the top speaker cover

    4 min

    Use a Phillips #00 screwdriver to remove the 14 screws holding down the top wireless charging coil and speaker assembly.

  7. 7

    Remove the wireless charging assembly

    2 min

    Gently pry up the wireless charging coil and top plastic speaker housing using a plastic spudger. Lift the entire assembly away from the phone.

  8. 8

    Disconnect the battery cable

    1 min

    Use the flat end of a spudger to pop the battery connector straight up off the motherboard socket. This cuts power to the board to prevent short circuits.

  9. 9

    Disconnect the main display flex cable

    1 min

    Locate the main display ribbon cable connected to the bottom of the logic board. Pry the connector straight up with a plastic spudger.

  10. 10

    Disconnect the interconnect flex cables

    2 min

    Disconnect the two daughterboard interconnect flex cables from the logic board using the tip of your spudger.

  11. 11

    Disconnect the front camera

    1 min

    Carefully pry the front-facing camera press connector up from the top section of the logic board.

  12. 12

    Unscrew the logic board retaining screw

    1 min

    Locate and remove the single Phillips #00 screw securing the top portion of the logic board to the frame.

  13. 13

    Remove the logic board

    2 min

    Gently lift the logic board out of the phone body starting from the bottom edge. Ensure no leftover cables catch on the board during removal.

  14. 14

    Position the replacement logic board

    2 min

    Carefully lower the new logic board into the frame, aligning the rear cameras and ports with their cutouts.

  15. 15

    Secure the logic board screw

    1 min

    Reinstall the single Phillips #00 screw to lock the motherboard securely to the phone frame.

  16. 16

    Reconnect all flex cables

    3 min

    Snap the front camera, interconnect flex cables, and display cable back into their designated motherboard sockets.

  17. 17

    Reconnect the battery

    1 min

    Press the battery flex connector straight down onto its motherboard socket until it clicks into place.

  18. 18

    Reinstall the wireless charging coil

    4 min

    Place the top speaker midframe and wireless charging coil back onto the device, aligning it properly. Secure it with the 14 Phillips #00 screws.

  19. 19

    Reseal the back cover

    3 min

    Clean remaining old adhesive with isopropyl alcohol, apply a fresh pre-cut adhesive seal, and press the rear cover firmly into place.

After your Samsung Galaxy S21 logic board repair

Power the Galaxy S21 back on and test the logic board repair function before you put every screw away. Check touch/display response, charging, cameras, buttons, and wireless as relevant to this repair. If something fails after closing the device, reopen carefully and reseat the connectors for this Samsung Galaxy S21 job before assuming the part is defective. Keep leftover adhesive and screws labeled in case you need a second pass.

Keep learning

Explore more Samsung Galaxy S21 repair context in the encyclopedia, or open related DIY guides.

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