ipad stuck on progress bar

iPad Mini is trying to update, but update is stuck on Apple logo with a very nearly completed progress bar.

I have let it sit as long as two days, hoping it would finish updating, but it never does.

I tried to connect it to my PC to update from iTunes, but iTunes is asking me to respond from my iPad before it will connect to my iPad, and there is no way to respond from my ipad because it is stuck on the update.

If I restart it, the screen just says "click here to complete update," then gets frozen at the end again.

Any advice?