Chosen Solution
iMac was dead- old logic board had no diagnostic LEDs. Apple store said needed new logic board a year ago (said they tried a new PS and no go). Just put in a new logic board. LED#1 lights up, but power button does nothing. No sounds, no fans, no HDD. I did add a SSD as a secondary device. There is another LED on right side that comes on/off when power button pressed (below DVD player). Could it be the power supply? Anything else? this is an iMac Intel 21.5” EMC 2428
Well, it wasn’t the power supply! Took everything apart and on one of the connecter I had bent a pin. Straightened it out, put everything back together and it started fine.
@turtleiron since you’ve already replaced the logic board and now only get LED 1 it is absolutely conceivable that this is a PS issue. Get one from a place that has a good return policy and try it out.
