Today I am dealing with a water damaged iPhone 6 plus.

It won’t boot up – the usual stuff.

Now hook it to USB cable and let it charge first, 30 mins passed, the phone becomes very hot, there must be a short in the circuit, let’s fix this first.

Opened up the shield covering CPU, found it is the backlit circuit, cap C1513 is shorted (circled). Removed it, now here is the second problem:

When it is powered on, current draw is big.

C1267 is also shorted, removed it, current draw now back to normal.

Now here is the third problem: finger print is not working.

Lets have a look at the voltage drop for each pins on the touch ID socket.

.

then, there are 2 pins (pin 2 & pin 4) value 0L on voltage drop,

so either the chip is broken or the trace on PCB is broken, in this case, is both.

Pin 4 is 1v8 power supply that goes through 3v converter , tested the fuse on pin 4 is fine- the chip U2100 that converts 3v to 1.8v is broken, replace it.

and then

pin 2 is 3v, above circled inductor FL2119 is broken, replaced it.

Bootup! baby.