That's scarry stuff to me!!! Did you use standoff's???????? of course you did,,, Right? I highly doubt it had anything to do with the screws. (but stranger things have happened, like it might be putting stress on a week trace or something like that) I bet you didn't have the psu atx connector all the way in, or you didn't have the extra 4pin connector in all the way. for future reference to test to see if the psu is toast just jump the light green wire (pin14) to any black wire in the 24pin atx mobo connector, then turn the switch on the psu on.