820-01521 No image on LCD but image on External Monitor fine

[No-Clean]

Water damaged board, ran it in UC, reflowed PM and the 2 CD3215 as I was only getting 5v after that board now starts up and I get image on external monitor, tested with 2 known good LCD screens and new LCD flex, no image either.

No shorts on LCD connector

SMC_LID Left and Right are both 1.5v
PANEL_P5V_EN 0v
PP5V_S0SW_LCD 0v

U8510 pin 1 0.9v

 

[2informaticos]

3V3/5V_S0SW_LCD must appear at least in the first few seconds.
Then LCD must release DP_INT_HPD.
If not, power cannot be maintained on LCD connector.
PCH needs the HPD signal to recognize the LCD properly.
The same PCH is the one which must start this sequence, releasing first EDP_PANEL_PWR_EN for few seconds.

"U8510 pin 1 0.9v"
This could be your unique problem; follow the trace...

 

[No-Clean]

Thanks, indeed it was pin 1 not getting 3.3v the problem, the weird thing is that the connection between R8511 and C8518 looked clean and there was no liquid damage near that area, but somehow those 2 were not connected via its traces.