I don't really know if this will work for you on a desktop but if you haven't already try disconnecting everything and holding the power button down for about 30 seconds, then reconnect it and try again.best I can do mate >_<
have you tried going to a repair shop yet
Trying to avoid that -_-
I just hit it with my hand near the on and off switch in the back and now it turned on yay!
Maybe it was off? :o