Teardown difficulty:
Moderate
Duration:
19 min

Recommended tools

Disassembly of the mobile device Samsung Galaxy S21 SM-G991 with each step description and the required set of tools.


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Step 1. Before disassembling!

⚠️ Before disassembling, do not forget to turn your phone off.


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Step 2. Remove the tray

Use the ejection tool (aka Needle) or Paperclip. Push the tip all the way into the hole until the tray ejects, and then pull the tray of SIM cards out.

⚠️ Pay attention! The tool must be inserted into a hole on the edge of the phone's housing. Do not press too hard. It may break the tray eject mechanism.


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Step 3. Open the back cover

We recommend using a special heating device such as a separator machine, heat gun, or heating mat. It will simplify the process. You can use a home hairdryer, but you will have to make a nozzle by hand or have a suitable one in the kit to gently heat and concentrate the heat flow in the right place.

ℹ️️ The surface of the back cover must be heated to soften the adhesive underneath. The approximate heating temperature is 50° C / 125° F.

Use a thin plastic film or pick for separation. To facilitate the process, you can use isopropyl alcohol. It is often most difficult to pass the tool between the parts to be divided. Choose the far edge from the FFC cables or buttons.

Do not use a lever or any force for separation that could damage the elements inside.


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Step 4. Unscrew the screws

Using a screwdriver (Tri-point Y00), unscrew two screws.

ℹ️️ Be sure to note the location of the screws before disassembling. When assembling the device, screwing the screw in the wrong place may damage the device or its part. To avoid damage, the removed screws and individual pieces (as gaskets or brackets) must be laid out in the appropriate order, or the screws and their holes in the phone must be marked with colored markers.


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Step 5. Unscrew the screws

Using a screwdriver (Phillips 1.5 mm PH000), unscrew 19 screws.


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Step 6. Remove the loudspeaker

Carefully remove the assembly of the cover, wireless charging/NFC tag, loudspeaker. 


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Step 7. Disconnect the battery connector

Disconnect the battery connector as soon as possible.

ℹ️️ The Samsung Galaxy S21 SM-G991 model has a battery EB-BG991ABY with 3880 mAh capacity (aka rechargeable battery).

⚠️ It is highly recommended to disconnect the connector to avoid possible short circuits during disassembly.

Also, try not to use a metal tool to disconnect the rechargeable battery connector or do it carefully.


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Step 8. Remove the earpiece speaker

Pry up the connector and remove the cover with an earpiece speaker.


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Step 9. Remove the inter-board cables

Carefully, preferably from the edge, disconnect the connectors and remove the inter-board cables connecting the mainboard to the daughterboard (also known as the sub-board).

⚠️ Be careful when removing the cables from the connectors, the cables are pretty thin, and it is easy enough to break them or damage the contact tracks inside.

ℹ️️ An arrow on the FFC cable (flexible flat cable) indicates its correct position.


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Step 10. Unscrew the screws

Using a screwdriver (Philips 1.5 mm PH000), unscrew three screws securing the sub-board.


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Step 11. Remove the daughterboard

Remove the sub-board. It is glued to the frame with metalized tape, so to facilitate the process, the sub-board can be heated a bit.

ℹ️️ The sub-board contains a charging port (Micro USB), microphone, spring contacts for the speaker, and an antenna unit.

⚠️ It is not necessary to insert the tool underneath when removing the sub-board. Internal components could be damaged.


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Step 12. Disconnect the connectors

Pry up the connectors of buttons cables, display module cable, front camera cable.

⚠️ Be careful when removing the cables from the connectors, the cables are pretty thin, and it is easy enough to break them or damage the contact tracks inside.


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Step 13. Remove the motherboard

Carefully remove the printed circuit board. There is no need to use a lever or try to reach the board by force. Make sure that nothing is getting in the way or holding the board.

⚠️ Do not bend the circuit board when removing it or push tools under it. Unbeknownst to yourself, you can damage components or cables from the inside.


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Step 14. Remove the rear camera

Pry up the connectors and remove the assembly of three rear cameras.

Detailed disassembly instructions of Samsung Galaxy S21 SM-G991 in the video, made by our mobile repair & service center:

If you have a question, ask us, and we will try to answer in as much detail as possible. If this article was helpful for you, please rate it.


Disassembling\Repair has medium complexity and takes about 19 minutes in time. Our manual is suitable for all models Samsung Galaxy S21 SM-G991 released for markets in different countries.



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