My computer, however, appears to have a toasted motherboard.
I am trying an eBay solution (suggested to me by the guy at the repair place who kindly did not charge me a bench fee for telling me that he was 75-80% sure my motherboard was the problem), which if it does not come through (or work ... the unit in question is being sold "as is" with no HD, but I've had no response on if the system is otherwise functional), leaves me off PC shopping.
This, of course, is putting a huge crimp in my "getting my job search stuff done" as I have all my files on the HD of the dead computer.
I knew I should have backed that up last week onto the portable HD that I'd bought a couple of weeks back. Bad Brendan! Stupid Brendan!