"Is it my hard drive or what?"
It could be, but it could also be shock damage to another component. It would be worth taking the back covers off and checking to see if there's anything obvious before you buy a new hard drive. You don't want to spend out for that, only to find there's some other problem.
If the hard drive had failed, the machine wouldn't start, and it is starting. The error code you see is usually associated with Windows activation, and there are fixes that you can try - here's one