I know this is an old topic, but I am having the same issue. At first, I wasn’t getting any diagnostic LED lights at all. I purchased and changed out the power supply and now I get LED#1 on when plugged in. Progress? Upon pressing the power button, nothing happens. No other LEDs come on, no sounds/fans. I went ahead and purchased another logic board, but the same thing is happening with this one too.
I have tested the power switch and it seems to be working. I get continuity between the wires when pushing the button.
My thoughts are that the power supply I purchased is bad, though I don’t know how to test it to verify. Does anyone know of a way to test it (voltage pinout) or have any other idea?
Also, do I need to completely reassemble the system to test it or should I be able to turn it on even without the LCD attached or logic board screws put back in just to see if it does turn on? Not sure if not having all screws back in would prevent it from powering on.
Thanks for the help.
the_buzz_man