Try setting the iPad in recovery mode:
connect the iPad to your computer
turn it completely off
press the power button (top button) for three (3) seconds
without letting go of the power button, press the Home button
keep them pressed for ten (10) seconds
after the ten seconds, let go of the power button without letting go of the Home button
keep pressing the Home button until a message pops in iTunes saying
iTunes has detected a device in recovery mode, you must restore it before you can use it.
restore the iPad
Try doing this a few times if you dont succeed the first time.