Ursprünglicher Beitrag von: Vince ,
My personal opinion is that there is something wrong with the LCD's inverter. I know if there is a short in any power supply the computer will shut down. The iMac runs on 5 and 3.3v but also has 12v fed through the Logic Board to the inverters. So if you have a shorted inverter it wont start up. You have a problem with the inverter or the video. And a connector for each one so you can unplug the power to the inverter on the logic board but leave the video connector in and if it starts up you have a bad inverter.