Turned off, won't turn on again, status LED constantly on?

Some time ago I came upon some issues with my iMac, I was getting kernel panics every now and then. I turned it back in on warranty, got GPU and motherboard replacements.

After that everything was running amazingly smooth for a year or such, but one day... My AirPort went crazy, I lost connection and wasn't able to do anything with it. Couldn't turn off the airport. Couldn't join networks. Other than that, computer was responsive, I could turn on/off other applications and such.

So I thought, heck, reboot and I'll see.

~sudo reboot

It turned off properly and never turned back on.

The status led (the one in the bottom right corner) is constantly on. I doesn't flash, doesn't blink, does nothing. Just shines my eyes away.

I tried resetting PRAM, PVRAM, hard reset by unplugging all devices and keeping it off the power for 5mn etc, #$*@ I tried all that I could find on Apple's support pages.

I must add that the iMac have had it's ram upgraded to 2x2gb sticks (system only recognized 3gb which I knew before). I replaced them back to original 2x512, didn't help.

I tried finding an answer every here and there but with no success at all.

Anyone? ;)

Mike