First thing you want to do is unplug the computer from the wall. Next, inside the case there should be a battery ( looks like a large watch battery) on the motherboard, pull it out. Close by the battery there should be three pins, two of which are covered by a piece of plastic, move it to the opposite position, covering the two pins on the opposite side. Now wait a minute... Put the piece of plastic back to the original setting, place the battery back in the motherboard, close the case, and plug it in. That should have reset things to default and allowed you to boot.