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ITDropping your HUAWEI Mate 40 Pro can be a heart-stopping moment, especially when you pick it up to find a black screen, a shattered rear cover, and disturbing signs of liquid crystal leakage. These damages can make your once-premium device seem beyond repair, but don’t worry—there’s hope. In this blog, we’ll walk you through a detailed, step-by-step guide on how to restore your HUAWEI Mate 40 Pro to its former glory.
Phone Details
Model: HUAWEI Mate 40 Pro
Announced: 2020, October 22
Defect Phenomenon
A HUAWEI Mate 40 Pro was dropped to the floor, causing the screen to turn black and the rear cover to crack into pieces. The upper corner of the screen also shows signs of liquid crystal leakage.
Troubleshooting
1: Screen Test
- Replace the damaged screen with a new one to test the display functionality.
- Despite the new screen, the phone still does not display, indicating the issue could be related to the display circuit or a boot problem.
2: Motherboard Inspection
- Remove the motherboard and perform a thorough cosmetic inspection.
- Discover that the motherboard is deformed and the DOCK flex cable connector is missing.
- The HUAWEI Mate 40 Pro has a double-layer structure motherboard with the 5G signal board soldered to it. The display connector is located on the 5G signal board.
- The no-display issue is likely due to a poor connection between the two layers of the motherboard.
3: Boot Test
- Connect the motherboard to a DC power supply and attempt to boot the device using tweezers.
- The boot current is normal, further pointing to a connection issue within the motherboard.
Repair Process
1: Separate the Motherboard Layers
- Place the motherboard on a PCB holder and use a hot air gun to heat and separate the two layers.
- After separation, observe that several pads are missing.
2: Repair the Missing Pads on the Main Motherboard
- Clean the pads on the main motherboard.
- Apply solder paste flux on the pads.
- Mix medium-temperature solder paste with high-temperature solder paste on the tin pads using a soldering iron.
- Thoroughly clean the pads with a solder wick.
3: Fix the Missing Pads
- Carefully scratch out the roots of the missing pads.
- For pads requiring jumper wires, make circles patiently.
- Apply a small amount of UV mask and cure it with a UV lamp.
- Scratch out the jumper wires once the UV mask is cured.
4: Repair the 5G Signal Board
- Scratch out the necessary pads on the 5G signal board.
- Resolder the board using a stencil and a hot air gun.
5: Recombine the Motherboard Layers:
- Reassemble the two layers of the motherboard and test the display using the original screen.
- The screen lights up normally, indicating the connection issue has been resolved.
Replace the DOCK Flex Cable Connector:
- Solder a new DOCK flex cable connector to the motherboard.
- With all issues fixed, the phone can be fully reassembled and tested.
Conclusion
The severe drop damage to the HUAWEI Mate 40 Pro, which resulted in a black screen and missing DOCK flex cable connector, was resolved by separating the motherboard layers, repairing missing pads, and resoldering the 5G signal board. After completing these repairs and replacing the DOCK flex cable connector, the phone’s display function was restored.
