There are many reasons that can cause iPhone stuck on Apple logo reboot loop, in our previous sharing, we have shared a case of iPhone X stuck on Apple logo reboot loop caused by defect flood illuminator module. In this article, we will share more details on troubleshooting iPhone X stuck on Apple logo reboot looop, and reveal how to fix the problem by chip level repair, we hope you enjoy our sharing.
Step 1 Function Test
Power on the iPhone and observe the screen. We found the iPhone stuck on Apple Logo reboot loop, and can’t enter the system
Step 2 Diagnosis
We have ruled out all the possibilities of phone parts defects that can cause the Apple logo reboot loop through a serial of tests, and therefore confirm the problem is caused by motherboard failure. Next we will further troubleshoot and fix the motherboard.
Step 3 Troubleshooting
Use the multimeter to measure the diode resistance of the battery connector, the resistance showed normal, which proving the battery circuit works normal. Then measure the compass circuit, and we discover the diode resistance of i2C main line is close to short circuit.
The reasons that can cause the i2C main line diode resistance short circuit are: capacitor C3552 failure, IC U5100 failure, IC U4900 failure or CPU failure. Based on our repairing experiences, the IC U5100 is more likely to get damaged, so we will start with troubleshooting U5100.
Step 4 Repairing
Take off the IC U5100 then remeasure the diode resistance, the value showed normal. so, it’s the defect IC U5100 that has caused the Apple Logo reboot problem. Replace a new IC U5100, then use the help of hot air gun and tweezers to solder.
Step 5 Reassemble & Test
Reassemble the motherboard then power on the iPhone, the iPhone works well, repair completed.
Please refer to below detailed video:
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Tools and Materials Used in This Video:
Hot air gun
Desoldeing braid/solder wick
iSclack suction pump