One night I restarted my imac and after a few min of booting up, it shut off and wouldnt come back on.

I did every trick I could find on the web and nothing.

Took it to apple genius bar, my warranty had just expired in may...they tried new power supply and nothing. New logic board, nothing again...so they called corporate and they told them its a "cascading" issue, meaning the power supply/logic board and even the back casing had to be replaced. Anybody even heard of this? it would cost me $1000 to fix it. anybody had the same problem?