You could verify this trivially by restoring the device with iTunes.
The disc doesn't actually need to be functional at all in order to do this. This won't magically fix anything, by any means, but what it will allow is for you to boot into Apple's diagnostic menu and confirm (very, very likely, with the information given), or deny, your fears.
Other points of interest are things like:
- Does the disk make any peculiar noises?
- Does the disk make any noise *at all*, can you feel/hear the platter spinning on boot?
[Saint]