820-00928, seems like brain dead

[donnos]

Hello, got a 00928 come in as water damaged but upon checking, liquid never hit the board. most on the LCD connector. nothing seems burned. diode reading on backlight output and MUX data pins are good.

right now macbook does not boot fully, no backlight or image either, using an external display i get the same black screen.
HOWEVER, I'm able to get to the startup manager by holding the option key, after selecting the drive i get no activity after this. This is on external display, nothing on recovery and nothing on diagnostic.

on the LCD i get nothing(known good LCD), i'm not getting EDP_BKLT_EN for backlight enable, i do have 5v and 3v3 going into the tcon.
i'm not sure if the no boot symptom is causing no display.

update** SMC bypass mode gives me low battery sign

 

[2informaticos]

Any liquid spill on LCD assembly affects MLB also; through J8500.

No reason to search for backlight, if you don't get image first on its LCD.
Low battery sign appeared on external monitor only?
Test the machine with known good battery.

 

[donnos]

low battery sign appearing on known good LCD, my guess is the orignal LCD is dead. but that does not explain why it does not boot
will try a battery first, but i thought the a1707 did not need a battery to boot and with battery i can't do smc bypass?

 

[donnos]

ok further updates,
When nothing is connected to board only screen, SMC bypass shows which showing low battery sign.
but when kb and tp is connected during smc bypass, i get high fan spin, and nothing after that.
no different with another battery, mac is not booting.
any ideas?

 

[2informaticos]

Test the board with external monitor; disconnect internal LCD.
Using charged battery, still get low battery sign?

KB/TP may be affected by liquid spill...