iPad froze during software update

After syncing, transferring all contents and backing up, I accepted the offer to update the operating software of my iPad I from 5.0 to 6.0. I entered additional password as required and the next time I looked at it, the screen was black with the Apple logo and 1/4 of the black line filled in white. It does not respond to holding down the power button, removing the syncing cable, restarting my iMac. All versions of software are up to date. If I try re-syncing it or repeating transfer from iTunes, nothing progresses in the message bar in iTunes beyond the attempt to start the sync. Is there anything to do other than attempt restoring it back to manufacturer setting?