820-02098 A2442 Backlight issue after water damage

[jxx]

Hello
This macbook does not work display backlight after water damage.
There was water damage on UP800
PP5V_S2_MAIN was short.
When I tested power supply, UP800 had a fever and I replaced UP800,CP818,CP817.
PP5V_S2_MAIN has no more shorts.

Everything seems normal, but the backlight still doesn't work. I got that chip from China and I tried replacing it with another chip.
Is this chip a set with other parts?
It was originally booted, but now it doesn't boot and it reboots indefinitely from Apple mark without the backlight.

 

[2informaticos]

Replacing BGA chips (even very small) on boards affected by liquid can cause weird issues.

Check all 0 ohm resistors around UP800; also be sure no corroded/broken trace in that area.

5V_S2 is stable now?

 

[jxx]

I'm sorry, but I don't know how to measure resistance.
black and red probes on pin 1 and 2 of RP830 in multimeter ohm mode and check if ohm 0 comes out?

 

[2informaticos]

You will not get exact 0 ohm; probes resistance included.
So expect 1-2 ohm readings...