iPad won't do anything
This is a bit fiddly, but you should be able to restore your iPad using iTunes on a Mac or Windows computer.

Please be aware that both of these options will restore your iPad to factory settings, so if you don't have a backup you will lose your data.

First thing to do is make sure you have the latest version of iTunes installed. Then connect your iPad to your computer and open iTunes.

If your iPad appears within iTunes then...


Select your iPad within iTunes and click the Restore button.
You'll be prompted to confirm that you want to restore to factory conditions. Click Restore to confirm you are okay with this, then iTunes will download a fresh copy of iOS and install it on your device. Click here for more info about this option.


However if it doesn't appear within iTunes then...


Unplug your iPad and turn it off completely. You should be able to do this by holding the power button on the top of the device until the display goes dark.
Then, with iTunes still open on your computer, hold in the home button on your iPad and reconnect it to your computer. Keep holding the home button on your iPad until the Connect to iTunes screen appears.
Once you see that screen you can release the home button and iTunes should tell you that it has detected a device in Recovery Mode that needs to be restored.
Select your device within iTunes and click the Restore button. As above you'll be asked to confirm you want to Restore your device, and if you confirm that, iTunes will download and install a fresh copy of iOS on your device. Click here for more info about this option.


Hope this helps.