Hard drive swap

[Shocker]

Hi,
Yesterday i made the mistake of standing on my Av500 yesterday by accident. When i stood on the device, it suddenly turned off. Now when i turn on the device, i cant access my files. So im thinking about swapping the old hard-drive that's in the device with new hard-drive of the same size and manufacturer. On another website they were saying that the hard-drive cant be swapped because the firmware checks the serial number of the hard-drive to make sure it hasn't been swapped. Is this true?
I also want to take the hard-drive out and connect it to my computer to try and recover some of the data on it. What size hex key is needed to remove the screw on the back of the hard-drive? I believe to take the hard-drive out there is two black screws to hold it in place. One on the side (I think it might be an M2) and a miniature one on the back.

Hope to hear a response soon,

Shocker