While working, my computer suddenly re-booted. Upon coming back up, I would get to windows, but then an Explorer error would come up, dealing with kernel32.dll. I figured it was either a virus or a random corrupted file, but after several attempts to fix it, including unsuccessful restore point resets, now the hd (WD 500gb) started clicking. Prior to this, no sound issues at all. So, figure it was bad sector, but what then changed (if anything) to cause the clicking? Any chance this is a pcb issue? And if so, do I understand it correctly that it's (nearly) impossible to swap out the pcb board successfully due to the eeprom issue? Thanks!

Forget it : as common WD failure, at least ONE head died if the drive starts clicking at POWER UP. If you can "see" the drive in BIOS it's one thing, if not (clicking at power up then eventually spin down) , it is internal failure.
In FL there are reputable members of this forum who can help you - but do not power the drive unnecessarily.

Thanks. How would I go about finding someone from FL on the forum?

Send PM to Quasimodo he is in Florida and very highly respected member of this forum. He should be able to help you out on this one

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Iorana Haraharaini

Agree. He can definitely handle this case.