Lenovo Ideapad G40 can't power on

Model : Lenovo Ideapad G40
Board id : ACLU1/ACLU2 UMA NM-A272 Rev 1.0

Laptop was water damage. After cleaning water damage, i found shorted 5V IC (PU905) and replaced with good one. Now 5V 3V is ok. When connect power, power led light open but can't power on. No cpu fan spin. Power consumption in DC Power Supply is 0.020 Amp.

PL303 - 3V
PL304 - 5V
PL307 - 1.3V
PL701 - 1.0V
PL302 - 1.89V
PL9 - 0V (Resistance to Ground on Coil PL9 - 61.3 Ohm)

Please help me to find the fault.

Hello!

Please, post a clear pictures of spilled areas of the board after the cleaning.

Does the power LED turn on automatically when you connect the power supply (without pressing to the power button)?

Yes. The power LED turn on automatically when I connect the power supply (without pressing to the power button).

With such a large spill area, there is unfortunately a very high chance that the APU hybrid is damaged.

I think the repair is not profitable in this case, because there are many other corroded components in addition to the APU hybrid that also needs to be replaced.

Yes. I agree with you. When APU is damaged, the repair is not profitable. But how can i know APU is damaged or not actually?

According to the symptoms and spill location, I can say that in 95% the APU is damaged.

If you want to waste the time, perform the following measurements:
- Measure the voltages to ground on both pins of quartz YC1.
- Measure the voltage to ground on pin 5 of PU301.
- Measure the voltages to ground on pins 2, 12, 14, 18, 21, 74, 86, 93, 108, 109, 110, 115, 116, 128 of KBC chip.

Does the machine turn off and stay turned off, if you hold down the power button?

I didn't mean that. You misunderstand me. Sorry for my english. I only want to know Why you decide APU is damage for Educational Purpose Only. For example you decide by your experience or something like that. By the way the power led turn off and on very quickly when i hold down the power button. ( LED Blink very quickly )

Voltages to ground on both pins of quartz YC1 - 0.37V and 0.33V

Voltage to ground on pin 5 of PU301 - 0V

KBC Chip
Pin 2 - 3.3V
Pin 12 - 1.8V
Pin 14 - 3.3V
Pin 18 - 0V
Pin 21 - 0V
Pin 74 - 3.3V
Pin 86 - 3.3V
Pin 93 - 3.3V
Pin 108 - 0V
Pin 109 - 3.3V
Pin 110 - 3.3V
Pin 115 - 3.3V
Pin 116 - 3.3V
Pin 128 - 3.3V

Lack of communication with the PCH.

Thank you all matic and Machine. Thanks for your helping and teaching. Case closed.