Malfunction Phenomenon
Try to press the power button to power on the phone, but the iPhone 7 Not Turn On with A Large Current.
Trouble Shooting
We checked the motherboard, there was no trace of deformation or water damaged.
Then connect the motherboard with the DC power supply, the current jumped to around 1.2A, which is very large.
Because the current is very large, some components should get very hot.
Connected the motherboard with the DC power supply and use the finger to touch the motherboard/ or use the thermal camera to locate the heated area, components around connector J3801 were found to be very hot, then use rosin inspection method to locate the exactly hot component.
The rosin on one capacitor C3828 gets melted immediately.
Then measure the diode value on the capacitor, the value was 0, which means the capacitor is shorted.
Remove the capacitor and test again, the short has gone, and current back to normal, the phone also can be turned on.
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