Firstly of all, we need to disassemble the iPhone X. Use phone opening tools to disassemble the iPhone X, disconnect the iPhone battery, and then remove the iPhone X display assembly.
Now we need to use UNI-UTP3305 DC power supply to measure the iPhone X. Connect the iPhone battery connector with the DC power supply cable, press the power button, the boot current is stuck on 110mA, which is abnormal.
SS-T12A preheating station to separate it, use tweezers to remove the iPhone upper layer and lower layer.
Clean the iPhone X lower layer by PCB cleaner, and then use qianli iSocket test fixture to test the iPhone X motherboard double layers, the boot current is abnormal. Remove the iPhone upper layer, and then measure it by DC power supply, the current is normal, so we can confirm that the iPhone upper layer is normal.
Use digital multimeter to measure the iPhone X lower layer, when measured S30 Pin, the didoe data measured is 40, while the normal value should be about 400. Check iPhone X schematic diagram, we know that S30 Pin is connected to U3400 L4 Pin, so we need to check U3400.
Use hot air gun and tweezers to remove the U3400 IC, we found the U3400 and solder pad have been badly corroded, and there are 3 components around the U3400 are corroded. Clean the solder pad, and then use hot air gun to remove these 3 components.
Install the new components to the motherboard, and then install the new IC to the motherboard. Measure the S30 Pin again, the valued measured is normal.
Now use Qianli double-sided jig to measure the iPhone X again, the boot current is normal. Finally, assemble the iPhone X, press the power button, the iPhone X can be turned on properly.