820-3126 Second LED Blinking

[tlough75]

I have on the surgery table an 820-3126 LB from an A1311 iMac that my customer worked on and may have inadvertently killed. I was able to suss out the main issue which is when he was replacing the GPU he swapped the power supply cable that is supposed to go to the LB for HDD power and put it into the output power to HDD connector. I found it by unplugging all the cables and would get a green light but as soon as I plugged in what I thought was the HDD LB power to HDD cable the lights would cut out. After I found the issue and swapped them, the second LED is blinking. I'm going to check around to see if there is any info but wanted to see if anyone knew if this is even fixable. Thank you for your time.

 

[2informaticos]

I remember to had a similar case.
Some resistor found burnt, I think.
You should check the HDD connector's lines which have been connected to 12V power rail.

 

[tlough75]

So an update on this one: I replaced the LED driver board, swapped LB and screen. It now boots but still no backlight. Gave it back to customer since I have put a lot of time into it already. I am at a loss of what it could be. I get 12v on the input connector to LED driver board and voltage on the output pins, but not lights. I logged on to it and saw that brightness was all the way up.