If the unit doesn't turn on at all, then i don't think the hdd is your problem. If the unit turns on, but wont recognize the hdd or says hdd corrupt or something like that then it sounds like a bad harddrive to me. I have 2 bad hard drives and they did the same thing. One updated to 99% then wouldn't go any further, and the other wouldn't work at all.
I am pretty sure that if you replace the hdd it will fix the problem, assuming the system still turns on somewhat. Another thing you could try is formatitng the hdd your have with your pc instead of the ps3 and then put it back in the ps3 and let it format it for its files and see if that helps. Good luck.