LED stays lit when I plug my iMac G5 in, but when I push the power button, LED 2 flickers on for less than a second and then goes off again. The iMac stays black.

I have tried to reset the SMU by plugging it in while holding the power button, but nothing has changed.

The computer became bricked after a brief power outage (and was the only machine in the house not on a power strip).

mayer wrote responding to "Where is a decoder for diagnostic LED pattern"

LED 1 indicates that trickle voltage from the power supply has been detected. This LED will be ON when the computer is turned off and your power supply is working correctly.

LED 2 indicates that the main logic board has detected proper power