iPhone 12 Pro drop damage and cannot boot issue repair
Defect Phenomenon
The phone was dropped damaged, and both the screen and back cover cracked seriously. Cannot boot, and the customer wants to keep the pictures inside.
Troubleshooting
Disassemble the phone and check the motherboard, the double-layer motherboard has almost been separated by the serious drop damage.
Remove the sticker on the NAND, it looks fine
Then heat with the hot air gun and heating platform to separate the motherboard thoroughly.
After separating, we can see the CPU also looks fine
Repair Process
The board inside the rails has cracked and broken, so the data recovery can be achieved by swapping the encrypted chip to another board.
First, remove the NAND chip and CPU very carefully.
Visit REWA Academy to learn the detailed soldering handwork from the REWA repair master.
Then clean the pads on the CPU, remove the glue, and reball it
Also, clean the pads on the NAND chip and reball it with the stencil, solder paste, and hot air gun.
Now, the most two important chips are well prepared.
In the next step, let’s solder the CPU onto the new motherboard.
Then swap the Logic EEPROM
Based on the repair experience, we can test the trigger current without installing the NAND chip first
The current reading is 80mA, it’s the normal DFU mode current value.
After testing, let’s solder back the NAND chip
Cooling down the board, then assemble the motherboard and try to boot
But it cannot boot normally. Guess it’s caused by the parts damage, maybe the dock flex cable, let’s boot the motherboard only with the screen and battery connected.
This time, the phone can boot normally
For the signal board, we need to reball the Baseband CPU and the Wi-Fi chip then solder them back to the motherboard.
Then clean the middle frame pads and bond the two layers of motherboard together.
Testing
After repairing, then assemble the phone to test all the functions. Everything is fine, only need to replace a new screen, then the phone can ‘Full Blood Resurrection’.
