iPad3 froze on update...

Try this first and see if the update will resume.

Reset the iPad by holding down on the sleep and home buttons at the same time for about 10-15 seconds until the Apple Logo appears - ignore the red slider if it appears on the screen - let go of the buttons. Let the iPad start up.

IF that does not help, you will need to restore your iPad and you will probably need to use recovery mode.

If you can't update or restore your iOS device

Excellent. You are quite welcome and I am glad to hear that all is well again.