blank screen and shuts down after 10 seconds
iMac G5 17 Model A1058
when pressing power button on g5 imac it makes startup noise but the screen does not do anyting and then it shuts itself down after about 10 seconds
Open it up by removing the back. There are four diagnostic lights on the logic board. Let us know what they are telling you. Also inspect the 24 "cans" capacitors for swelling and/or corrosion.
I have the same problem: the boot up sound and the fans and HDD working but no picture on the screen. My leds 1, 2 and 3 are green and 4 is off.