Error 23 trying to restore original iPad from iTunes
From Resolve iOS update and restore errors

Check for hardware issues
Related errors: 1, 3, 10, 11, 12, 13, 14, 16, 20, 21, 23, 26, 27, 28, 29, 34, 35, 36, 37, 40, 1000, 1002, 1004, 1011, 1012, 1014, 1667, or 1669.

These errors mean that your device or computer may have a hardware issue that's preventing the update or restore from completing.


Check that your security software and settings aren't preventing your device from communicating with the Apple update server.
Then try to restore your iOS device two more times while connected with a cable, computer, and network you know are good.
Confirm that your security software and settings are allowing communication between your device and update servers.
If you still see the error message when you update or restore, contact Apple support.