MacBook Pro 820-02841 Not Booting

[Instafixx]

Machine came in with no booting. Amp Meter rebooting at 5V.
Corrosion on the back side . Entirely at the below area UA200/UA600.
Changed many caps and resistors. Now goes upto 20V and stays there for about 10 seconds and then reboots. Draws 2.9 Amps as well - which is pretty good.
No Mouse Click.
I was checking parts randomly PPVOUT_LUXE_XW diade mode to ground is 0.010. I don't know if its correct.

 

[2informaticos]

Is that reading without LCD connected?
If yes, the filter caps CP830-5 are the first suspects.

 

[Instafixx]

I remove all. Still short remains. Injected 1V. Short Gone.
Put back all caps. Again short. Injected 1V. Again short gone. Its stable now.
PP3v8_AON was shorted.
Removed RD672. Short at PP3V8_AON_SPMU .
Injected voltage led to U7700 heating up.
Replaced.
PP3V8_AON_SPMU now ok
PP3V8_AON diode mode to ground is 0.159. I think it's shorted. But it is not pulling any amps.
I put back RD672 and tried to boot up but machine now stuck at 5V and 0 amps.

 

[2informaticos]

If now 3V8_AON is stable, check U8100 & U7700 LDOs.

 

[Instafixx]

Not getting PPBUS or 3V8_AON all around 0V to 1V.

Found UP800 to be corroded. Removing it removed the short of PPVOUT_LUXE_XW. Will have to replace this backlight ic.
But board still behaving the same way.

 

[2informaticos]

So you get 3V8_AON only if remove RD672?

 

[Instafixx]

No.

 

[2informaticos]

"Removed RD672. Short at PP3V8_AON_SPMU .
Injected voltage led to U7700 heating up.
Replaced.
PP3V8_AON_SPMU now ok"
???

 

[Instafixx]

Short was removed. not getting voltage there.

 

[2informaticos]

3V8_AON was present when you got 20V input.
So check the job you did on the board.

PPBUS_AON is stable now?

 

[Instafixx]

U5000 also fried. I think that's 3v8_aon vanished.