820-01987 trackpad clicks but nothing on screen

[ytesfay80]

I have this board that was sent in for water damage. When I plugged it in the trackpad would click and the ammeter read 19.8v and 0.55A
The only components that looked like they had any kind of liquid damage were C8412 , C7660 and Q7660. I replaced C7660 and C8412 and put the board in the ultrasonic.

Now the board is still doing the same thing except now the amps keep going up all the way until 2.49A but still nothing on the screen.
L7670 is showing 5v

I'm not sure exactly where to start troubleshooting since the trackpad still works and gets power to it and if I measured correctly I dont think there was any voltage on PPVCC_S0_CPU.

 

[2informaticos]

Check other S3 and S0 voltages on the coils.
Now it gets 2.49A from charger w/, or w/o battery?

 

[ytesfay80]

That was with the battery in. Wout the battery it goes to 0.05A for a couple seconds then stays at 0A.

I checked for voltages on PP1v2_S3, PP1v8_S5 and PP3v3_S5 and they had 0v.
L7690(PP3v3_G3H) has 3.3v on it and L7030

 

[2informaticos]

Post PM_SLP_S4_L and PM_SLP_S3_L levels.
Mention if not present, but pulsing (if is the case).

 

[ytesfay80]

From what I saw there was no voltage or pulsing on neither PM_SLP_S4_L or PM_SLP_S3_L.

 

[2informaticos]

Trigger SMC_ONOFF_L and check for drop pulse at PM_PWRBTN_L.
Be sure PM_RSMRST_L is steady high.

 

[ytesfay80]

I couldnt find the ONOFF lines for this board because the board view I have is on a pdf file.
I checked for voltage on PM_RSMRST_L and PM_PWRBTN_L on R1800 and R1802 and got 0v on both.

 

[2informaticos]

Try DFU mode...

 

[ytesfay80]

I booted in DFU mode. Initially I tried to revive firmware but I never saw anything appear on the screen like I have in the past then it froze so I cancelled it and restored the firmware.

Again I didn't see anything appear on the screen then this image appeared on the screen that said booted(Image attached).

Now when I try booting in DFU mode it won't let me restore or revive it and gives the message I also linked below.

When I turn boot to an external monitor I don't get any image either.

 

[2informaticos]

You can try to reflash U4770, SoC ROM, with a good dump from other board.
Some people claim on Internet they solved not booting boards this way.

Is just something to try.
Make backup of the content first.