820-3437 No Image, No Chime.

U6100 and its surroundings look good, seems to have some liquid damage, corrosion around some traces but nothing major. I have cleaned up most traces that look bad but board still does not completely turn on.

All power rails are there, board starts out at 350 Mah, then goes to about 600 Mah or so, as if the board was turning on but still no image or chime.
USB Activity is present, no external video either. Seems like a bad BIOS (ME Region possibly).

However there seems to be some small blue crap near the SMC, could have corrosion inside of it. Should I replace BIOS chip with new ME Region and EFI from a donor board, then if that does not work replace or reball SMC?


Staff member
Reball SMC, if was liquid spilled close to it.

Did you properly test USB activity?
Just using USB mouse is not sufficient sometime.
I dont test with USB mouse, I test with USB drive that contains a MacOS Yosemite Install.

Im going to order an SMC stencil and reball.

Will report back when done.

EDIT: I know if there is USB activity because when the drive is being searched or accessed it will repeatedly flash a LED light, there is only an ON light, no flash for activity.

EDIT 2: Removed Quote
Last edited:


Staff member
Do not quote an entire post, visible few centimeters above.
Maintain forum aesthetic please.

"there is only an ON light, no flash for activity. "
So no USB activity confirmed in your case?
I dont know how I quoted the entire post, I know the forum rules, I did not mean to do that, sorry!

No USB activity confirmed. USB Power is present, NO activity.

Should I enter SMC bypass mode to confirm this is an SMC problem?


Staff member
If you do not use Medusa programmer, remove J6100.
Also check all SPI Bus Series Termination resistors and their traces.
If all good, try known good BIOS...
Ok, I will remove J6100

I will reflash U6100 by desoldering and using a clean ME and good BIOS.

Do you know where I can get a good 820-3437 BIOS? All I have are 820-00165 BIOS.