I would think it much more likely that you need to take the parts out of the PC and plug them back in together. Basically, something vibrated enough to not make contact.
I don't think powering on a PC without a ground connector would necessarily fry it. Did you hear any zapping sounds or smell burnt electronics after you plugged it in or turned it on?
If not, then it may be as simple as needing to re-seat RAM, and unplug / replug your SATA cables.