All the drive activity of the trojan loader and removal efforts probably ended its miserable life, but it was showing signs of trouble for a long time. Bootups took longer and longer, etc., and files corrupted, but scandisk never found anything wrong when it did run.
People who write trojan loaders, etc do NOT want the machine disabled. They NEED a running machine to sell for their botnets. A broken machine is of no value to them...So I do not regard it as an atack per se.
Anyway, recovering the data from a badly infected drive may not be the best answer anyway. It's like digging up the corpse of a plague victim.
I was thinking it could be the BIOS.
Years ago in the mid 90’s I had a black screen and of course we are to make a copy of our hard drive which I never did.
But one can go to Statbles etc they have that CD back up for almost all kinds of computers to restore the BIOS.
How to enter the BIOS or CMOS setup
http://www.computerhope.com/issues/ch000192.htm