been an indicator that the HD on your iBook failed during the data transfer.
Find the OS X installation disk, or the disks that came with the iBook, and boot from it.
Once booted, start the installation process and as soon as the menu bar appears, open the Utilities.
From there, run Disk First Aid.
If you cannot see any hard drive, then it is a sure sign that it has failed.
Disk Warrior has been known to resurrect drives in this state but the drive has to be spinning for it to work. Stick your ear on the case and see if you can hear the drive spinning.
Replacement Hard Drive could be in your future.
While I was in Target Mode transferring files from my iBook G4 to my desktop iMac it got hungup and quit doing anything except showing the spinning beachball. In frustration I shut down the Target computer (iBook G4) by holding down the power button and then did the same thing to shut down the iMac. Now the iBook won't start up. Apparently it can't find it's hard drive. Both computers are running OS 10.4.11. The iMac is working fine. What do I do to fix the start up on my iBook??