I got a pc here that also went threw a fire. worked for a few hours then quit. but mine went to a cleaning co. that suposidly cleans it with a solution then lets them dry out.
here a few ?s for you...
when you plug it in and hit the power button does it do anything? do any fans run? how much smoke got in there, is it all covered with that sticky crap? did those firemen hose the thing down?
Ive had a few power buttons on cases go bad. you can follow the 2 wires from the power button to the motherboard, unplug, use something metal (screwdriver) to jump the 2 pins.