Tried disconnecting all peripherals and the hold the power button thing, then the plug in the power cord while holding the button thing.; nada, zip, zilch, no sign of life. This may be from an electrical storm; the iMac is on a good surge suppressor, and it's companion Dell 30" monitor is fine. When I left, it worked; when I came home, it was dead. It's out of warranty; I'm fully capable of taking it apart, fixing it etc. So, take it to the Apple Store or buy some specialized tools and have at it?? Any thoughts or suggestions welcome!