Overheating iMac

 A few years back I did something silly even though I knew I should not do it.  I had a CRT iMac in my room that didn't have a seperate monitor switch and I wanted to get some sleep.  Because the display was too bright for me to get to sleep, I covered the iMac with a couple of towels and of course it overheated and would not turn back on.  I then searched Apple's knowledgebase and it told me to open up the unit and find a red PMU (Power Management Unit) button to reset the motherboard.  I did this and all was fine, thank God!