Sometimes older ATX cases had buttons that stuck if pushed in too hard. The circut in the switch could not close and so the computer won't turn on. I have solved a number of these issues by give the case a swift bang on the side on line with the switch. This has previously caused the switches to jump loose. I take no responsibility for any damaged caused !! It has worked in the past. Alternatively get to your local PC shop and buy an new case for around £25.00 and move all the bits to the new case, not too dificult. Most plugs will only go in one hole, if only life were as simply !
Chris, June 2005