As you know, installing a HDD in a pre-unibody MBP requires removing several pieces of tape and moving some wires around. Open the MBP and check carefully that all wiring is in position and connected. you may have inadvertently disconnected something.
If no success, an appointment at an Apple store genius bar is the best option.
I fixed the issue. I researched many many forums and found no help on any of them, and sorry-no help on this one either.
What solved the issue - and I hope this helps someone else who has the same problem:
1). Install new hard drive (with or without osx pre installed)
2). Remove all ram
3). Power on and wait 1 minute
4). Hold power button until it turns off
5). Install ram
6). Power back on
7). BOOM! It works again.