Help! I can't install OS on new HD

Question

Help!!!
About 3 weeks ago my iBook G4 1.2 GHz fell off of a desk about 2.5 feet off the ground and landed on it's front edge. Right after then, I picked it up, and it seemed fine, just that it was frozen, so I restarted it expecting it to come right back up... it did load right back up, but would freeze after a few moments of use. After restarting, it would do the same. I checked on a few other related posts and found that it could be the hard drive or the ATA controller, so I made a gamble and bought a new HD (not a bad price and I got an extra 70 gigs of space) and tonight I just installed it, so I put in the OS installation DVD and tried running it, but after it got past the DVD verification process, it froze.
I've tried running the Disk Utility quite a few times to fix the HD (I was able to format the HD on one occasion) but each time I try to verify and fix the HD it just comes up with an error saying that the disk can't be unmounted, so therefore can't be fixed.
This was about the same thing that was happening on my original hard drive, so I'm coming to the conclusion that there's something else wrong (I'm a smart one, aren't I?)
If anyone knows of any other possible solutions to this problem, I'd love the help!
Thanks!

Answer 1

Only additional troubleshooting ideas come to mind; not repairing the real
problem, in that may involve a logicboard [or controller not sold separately?]
There was a powerbook fixit site that offers parts, repairs and some tech
pages of helpful to out-of-warranty Apple portable users; it may have a
few hints and tips, and take-apart details to allow further exploration inside.
Some have a good view of all the parts; and maybe a sub-assembly
could be acquired from a parts supplier, if you narrow down the field.
If you had an external Firewire enclosed drive, you could try booting that
defective computer from there; an installation on a good, properly formatted
hard drive inside such a case may give you further ideas on how damaged
the computer is. And you try running the different tests from the booted
OSX computer install/restore/hardware test disc included with the Mac.
Assuming the optical drive still works, you could maybe install a test OS
on to an external to further play around, too. (Could any cables be bad?)
If the logic board does not need replacing, that would be very good; at
some point, it may be worth sending the 'Book away to some qualified
service repair facility and see what they have to say about it. Some
charge about $50. to get into the non-display part of an iBook; total
cost would be that labor plus parts, at places like wegenermedia.com.
Some companies may take a broken one in as a core toward
the purchase of a repaired computer in their stock; ask around.
Hopeful it'd only be a data cable, etc you can replace; over-optimistic?
Best wishes, nonetheless!