Hello,
my son has a older pc with a Shutle MotherBoard a AK-38 i think thats it a AMD Athlon 2400Processer with 768 ddr ram a 256 NVIDIA video card, and out of the blue it wont boot, cpu fan runs case fan runs, and the lite beside the ram lites up, the hard drive wont start the dvd rom wont open unless i unplug the cables, i have tried putting another batt in but no luck i pulled cpu out and put back in and new heat grease on it no help no beeps no sounds just dead, no BIOS , the green lite on the monitor stays orange i have tried another monitor and video card , i have took ram out put 1 stick in at a time.
Any help or ideas would be great.

Thanks

Three top causes;

1. Power Supply
2. CPU
3. Motherboard

If you have access to another (comparable) P.S., swap it out and try booting.
If not, pick up a power supply tester at any major computer store. There's cheap, and there's expensive. Try to go at least in the middle. $25.00 US or so should do it.

If it is the power supply, it may have damaged the CPU or Motherboard.

For CPU & motherboard, without expensive equipment, the only thing you can do is a component swap. Without components, your recourse is a repair center.