My wifi is turned off, and no matter what I do, it will not turn back on

Have you tried doing a network reset?

1. From a Home screen, navigate: Settings > General > Reset.
2. Tap Reset Network Settings.
3. If prompted, enter passcode
4. Tap Reset Network Settings.

It maybe a hardware fault or something resolved by a complete reset of the iPad. You could try the latter before having to send it off for repair.