820-2936-A won't boot to OS, stop at loading bar

djdblaster

New member
Board is clean. No history available. I'll guess it could have been dropped.

It doesn't want to load OS. Stops at loading bar at the very end. Something holding it back.
 

djdblaster

New member
Forgot to say that it won?t boot with bare board only. Screen and external good drive are connected. I?ve even tried pendrive OSX, but nothing.
 

JohnB8812

New member
Ohhh gotcha. Yeah this one could suck. PCH getting burning hot by chance? This could really be anything, so inspect very closely for any hints of corrosion near SMC, U1900, the BIOS etc.
 

2informaticos

Administrator
Staff member
PRAM reset done?
Tried SMC bypass mode?
This could be a sign of corrupted ME also.
ASD EFI reports any error?
Try one RAM module at a time.
 

djdblaster

New member
PRAM, SMC and RAM one at a time - no change.
Shall I try to reflash BIOS? (ofc save backup)
Maybe first go with ASD EFI?
 

djdblaster

New member
I've done BIOS. No change. I see that SMC area doesn't have glue around, might have been reworked before. That's the only sign that I can see on this board.

The work that has been done on this board is LCD connector replacement. Customer claims it worked before replacement. I don't see any reason why a connector would be stopping it from booting, except that backlight driver could be misbehaving on SCL and SDA lines?
 

djdblaster

New member
Not sure. I've downloaded one that's supposed to be "clean" from Ghostlyhaks Forum. Used it already before for other machines, they turned on fine.

I've mounted SSD to it with SATA cable. It loads instantly to 3/4 then goes really slow.
 

djdblaster

New member
Thank you Duke and everyone else.
Unfortunately, I cannot find anything on this board that could be holding it from booting, unless I go piece by piece by comparing to a known good, which would take time.
 
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