Hhhmmm.... I wanted to add this to the "power supply" post but I guess its locked. So Im working on an HP p6-2100 desktop. It is getting power because the green light in the back illuminates with no issue but the start/stop/power button is doing nothing. I tried changing out the CMOS battery already with no results. Am I going to have to actually change this button? What else can I look at? I barely remember how to add pic to these posts, lol, but I can get you what you need to advise.
PS The lady who owns it thinks, her then dying cats, pee may have dripped down on said power button and somehow shorted it out. For awhile she was able to jiggle it and get a response.