I have an Emachines 420 with IM845GV motherboard. When I try to switch it on, the front panel LED lights up but nothing else. There is an electrical noise when I remove and replace the lead in the power socket. The previous evening, we did have a short power cut - the PC was not on but was plugged in. There is no burning smell inside the PC anywhere and everything looks fine inside. I hope someone can give me some advice to get it going again.
It's nothing to do with telephone lines or modem. I would suspect either the front panel on/off switch or its wiring to the front panel connector on the m/b or, if you believe that is OK, it sounds like a m/b problem.
If there was no surge protection around the power cut and the computer was connected to the wall plug then this sounds very much like damage to the motherboard caused by the power surge when the power supply was restored. It could also be damage to the front panel as described above
The basic answer is fairly simple testing by a local computer shop I'm afraid