Hi there, I just recently got back from going on vacation and I came back to find that my iMac G5 (with ambient light sensor but no built-in iSight) no longer turns on. If I press the power button absolutely nothing happens. So I tried other power cables and outlets etc, which made no difference but I did notice that when I plug in the power cable I can hear a loud hissing sound. I decided to take the cover off and take a look at the diagnostic LEDs and only the first one lights up and using the internal power button seems to make no difference. I also tried resetting the SMU but that didn't seem to do a lot. Anyone have any ideas what else I could try? I was also told that while I was away there were many storms in my area so I just hope there weren't any power spikes/surges that may have damaged the hardware somehow.