More and more people reported that their iPhone was stuck in a restarting loop. The phone continuously restarted and became totally unusable; the Apple
1. Take down the LCD screen assembly
2. Test the voltage of the battery with the digital multimeter. The battery voltage is 4.21V, and the battery test signal voltage is 2.02V. The battery is normal, so we install the LCD screen assembly to check other malfunctions.
3. Failure detection: connect the phone to computer, it could not be restored by iTunes, an unknown error occurred (9) so that we can draw a conclusion that NAND flash or CPU is cracked
4. Detach the motherboard from the phone, and fix it on PCB holder.
5. Remove the NAND flash chip from motherboard carefully.
6. Clean the bonding pad with the Soldering iron , knife, Bga Paste / flux rosin, wick and PCB cleaner.
7. Connect the NAND flash programmer with the computer, transfer the data from the old NAND flash to a new one.
8. New NAND flash chip BGA rebelling.
9. Install the new NAND flash chip to the motherboard.
10. Install the motherboard to the phone.
11. Restarting and testing everything is working normally.