Chosen Solution
First time today, tried to turn on my iMac and no power, no beeps, no nothing. Unplugged all USB devices, still nothing. Unplugged the power cable, waited 30 secs or so, plugged it back in, waited another 20 secs. or so and it powered up. Shutdown, then pressed the power button, it came right on. Shutdown completely, waited about 5 mins. and tried to power back on, nothing. Unplugged for about 30 mins. Plugged it back in and it powered right up. Is this a sign of the power supply maybe going bad or could the power button be the issue? I’m not sure by clearing the SMC solved anything.
Open it enough so that you can observe the diagnostic LEDs to the right of the RAM slots to see if #1 LED is staying on, indication that the power supply is getting trickle power and let us know. Also observe how much dust is inside. Be careful that the screen does not drop and rip out the video cable while doing this.
