Have you tried entering DFU mode?
DFU mode will allow the ipad to bypass any OS related issues in order to perform a proper restore/reset.
Connect the ipad to the computer.
Turn off the ipad, and wait 5 minutes.
Press and hold the power button.
As soon as the apple logo appears, press and hold the home button (continue to hold the power button as well) until the device connects to the computer.
At no point should the ipad fully boot/show the "connect to intunes" image
If the ipad boots or shows the "connect to itunes" image, you are not in DFU mode.