A few powersupplies have a "safety feature" where if they're unplugged you need to toggle the switch on the back and/or pull the cord out. None of my power supplies needed that, but I knew someone whose supply had that kind of "safety feature" and it was annoying... So just plug it in, rock the switch on the back to off, wait a few secs, rock it on and try. Then maybe unplug, play with the switch, etc. See if that changes anything...


Otherwise open it up and make sure the power button on the front is connected to the right headers on the motherboard. It could be the button worked loose or something...but I'm not exactly sure what's up since I can't physically examine the machine...