I've just opened ip up and double checked all connections, same problem.
Trying that now.
I think it must be a board issue, as Disk Utility just can't see the disk.
The only thing you can try and do now is Apple Hardware Test and if there are any Errors in it.
Lets say the Logic board is the problem, you can still use it, USB is working, booting OS X from USB works, not handy but for a desktop it works.
It still might be the Cable, she might have dropped it.