"Something else, I assume you know that if you get the polarity wrong on any of the pin connectors, the machine will not boot. Could fry the drive as well."
OOps, my previous post was for you.
If it is not a shorted floppy or cd drive,(un plug at the power and data connector, one at a time and try to boot) then it must be the hard drive.
A bad drive acts the same way. nothing happens. Or you get a clicking which is a failed boot attempt.
I'm guessing it got popped by a line surge caused by a storm or something.