Chosen Solution
I just hit a dead end. Someone gave me a broken A1312 so I thought I could fix it. At first, the diagnostic LED 1 stayed on. But it wouldn’t turn (No LED 2, 3, 4)on when I press power button. I took a step and try to check power button by wiring two pins together. Nothing. So it shouldn’t be the power button issue. Next I changed power supply; bought used one from reputable seller. Same issue. LED 1 stayed on, but wouldn’t start after pressing power button. (No LED 2, 3, 4) Next I changed the logic board; again, bought used one from online reputable seller. SAME THING! LED 1 stays on, but not turning on when pressing power button. (No LED 2, 3, 4) Is there another step of trouble shoot for LED 1 is on but not turning on? FIY, I always plugged into the wall directly. Even tried different 3-prong cables. Please help. Now I’m in ~$150 with parts with this computer :(
My first bet would be that you got a bad power supply from your reseller. This has happened to me several times. You can also end up with a partially functioning PSU. But the fact that you never got the #2 LED to light is the telltale. These part numbers will work for you 661-5310, 661-5468, 661-5972.
