No power to board

I am attempting to fix my friends computer. It is a gateway 310x, with everything stock except for a 1gb crucial pc2700 ddr 333mhz ram stick. I have individually tested each part of the computer in a different pc to see what was wrong. I assumed that the motherboard was fried so I buoght a new one the same model. Now after installing i have the same problem.
When i plug the psu into the pc i see a green led and if I hit the test switch on the psu I see a steady red led. The cpu fan starts as well when i do this. But no video.
This problem first started when my friend noticed that his internet was really slow, so he tried to power down his modem and pc. When he went to turn the pc back on it didn't start.

The processor may be fried not allowing it to power up , also if the processor fan is burnt out it won't start up either , also if any hardware is has failed and is crossing over it won't start