820-00840 Liquid damage - Turns on slowly and won't boot SSD or USB.

Mattpd

New member
First time working on a USB-C board...

Liquid hit U8210 and U3200. No visible corrosion, just sticky mess. The rest of the board looks flawless.

Cleaned up U8210 and verified PP3v3_S4 and PP5v_S0 are being output.

Flowed flux at low temp and ultrasonic cleaned to attempt to remove anything under U3200.

Upon inserting USB-C (either port) it takes 20.4v and 0.65A and fans start but screen remains off.

The amps slowly climb from 0.65A to 2.95A and after about 45 - 50 seconds the screen will come on.

With customer's SSD installed I get flashing ? folder once machine turns on. SSD is warm (borderline hot). Zero liquid damage in the area of SSD though. Unfortunately I don't have another A1708 on hand or another one of these SSDs...

I attempted to boot from a known good test drive over USB. It will give Apple logo, no loading bar, and gets stuck forever.

I also attempted to boot from two newly created USB installers. They also give Apple logo, progress bar starts, then machine reboots...

Lastly I tried diagnostic/internet recovery. It shows that there are no available wifi network.

It is possible corrosion under U3200 would cause all of this? I have a new on on the way just in case.
 

2informaticos

Administrator
Staff member
U3200 should be good if you get now 20V on both USB-C ports.

Try USB macOS disconnecting internal SSD first.
 

2informaticos

Administrator
Staff member
Do NOT quote entire post, visible few centimeters above.
Please, maintain forum aesthetic.

Try to boot Linux Live, or Windows through USB.
You may need to clean ME in BIOS...
 

Mattpd

New member
same result with that BIOS too.

When I tried to PRAM reset I held the buttons for the 50 seconds and the screen lit up but nothing on the display. It remained lit for about 10 seconds and then the machine turned off and didn't auto-power on again. Does PRAM reset work differently on this model?
 

2informaticos

Administrator
Staff member
Something strange, if PRAM reset doesn't work properly.
Do you have Medusa programmer?
It can also reset NVRAM...
 

2informaticos

Administrator
Staff member
Do you get correct voltage at U8210 outputs?

The BIOS in the link should have PRAM reset done with Medusa.
I don't have another BIOS for 00840.
Upload original BIOS of your board and I will try to clean it.
 
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