Here is an iPhone 6S that was damaged by water, now the iPhone 6S doesn't boot, it leaks 120mA after connecting to the DC power supply, when trigger it, the current is stuck in 360mA. Here is a solution to fix it.
Take out the iPhone motherboard, put it under the microscope to observe, finding that the iPhone baseband power IC, NFC IC, iPhone big audio IC and iPhone display power IC all have traces of water.
Attach iPhone motherboard to the PCB holder fixture, and then use PCB cleaner to clean the iPhone motherboard. Connect iPhone motherboard to the DC power supply again to observe the current, now the now the current turns to 80mA, after triggering, the current is stuck in 300mA. At the same time, we found the iPhone display power IC was repaired before, and the corner of iPhone display power IC was damaged.
Remove the iPhone
display power IC, re-connect to DC power supply, the iPhone motherboard is no
longer leaking. Trigger it again, now the current is stuck in 240mA. According
to our experience, the current directly ups to 240mA after triggering, it
should be caused by power supply short-circuit of LDO that output from the
iPhone main power supply.
Use digital multimeter to measure the
diode data of the LDO power supply that output from iPhone main power, we found
the fingerprint 3V power supply was short-circuited.
For the
short-circuit problem, we should use rosin method. First use QUICK 861DW hot air rework station to smoked the fingerprint 3V power supply
area till it turns white color, and then add 3V voltage to the fingerprint 3V
power supply position, we found the rosin of a capacitor melted.
Check iPhone PCB
bitmap via ZXW Dongle, we found this capacitor is C4104. Remove the C4104,
and then measure the diode data of fingerprint 3V power supply again, now the
data is back to normal. Measure the current again, now the current tested is normal.
Solder the iPhone display power IC to the iPhone motherboard, and then assemble the iPhone. Press the iPhone power button as usual, now the iPhone 6S is turning on smoothly. After entering the IOS system, all functions tested are normal.

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