Solved: iPhone 7 won't boot and almost dead after dropping

Recently, we received one dropped iPhone 7 and one iPhone with iCloud lock from our customer, the customer describes the iPhone 7 was dropped, which without iCloud, but it doesn't boot. The customer wants us to fix it, and then change it to the iPhone which with iCloud lock. But now, we need to fix the dropped iPhone first.

After checking, the iPhone is hurting a lot by a serious drop. The screws on motherboard have been dumped, as shown in picture 6-3-1.

Connect it to UD 1505TA DC power supply first, it shows large current leakage. After measuring, we found the iPhone NAND flash 3V power supply was short circuit. After observation, we found the iPhone motherboard slot position is bent; the short circuit may also be in this position. After remove the two capacitors, which on the side of the NAND flash, detecting it again with DC power supply, now it can be turn on normally.

Turn on iPhone and test functions on iPhone, we found there is no WIFI; sometimes it will be stuck when into the settings. After measuring with Fluke 15B+ Digital Multimeter, the side of wife clock signal r0807 has 1.8V, the other side which is through to wifi module 17 pin has no voltage. Replace the resistance, and weld the jump wire by QUICK 861DWrework station, the fault is still exist. Decisively remove Wi-Fi module, and then the solder pad drops points, it is common in the iPhone that dropped, weld the jump wire first, as shown in picture 6-3-3.

 The WIFI module also drop points, we can check it under the 7-45X Trinocular stereo microscope. We want to test functions by turn on iPhone without installing Wi-Fi module, but when apply power on it, it's leaking again. Now, we need to use the rosin methods to fix it.  After remove the heating capacitor, power on iPhone and test it, the setting function is normal now. Next we need to install WiFi module, after finish it, test the function, the Wi-Fi is back to normal. However, sometimes it restarts automatically.

Considering there is a slight distortion in the middle of the iPhone motherboard, the audio can cause a reboot, so we remove the audio first, also drops points. After soldering jump wire, turn on iPhone and test it, all functions is normal now.

Now we need to replace external configuration. Use JM-P01 Essential Electronics Toolkit to disassemble the iPhone that with iCloud lock, please be careful not to break the line of the iPhone. Then replace the fingerprint that on the iPhone screen, because the under of fingerprint have glue, so please be careful not to damage the IC.

Finally, install the repaired motherboard, assemble the iPhone, turn it on and test it, now all is normal. The iPhone 7 has been repaired!