iPad Air 2 has locked me out since upgrading to IOS 8.3

I have always been reluctant to upgrade to new software versions at least for a few days as they inevitably have issues within them that cause more problems than they fix. However, having given it a good few days I finally gave in and "upgraded" to 8.3 on my iPad Air 2. DISASTER!

When it rebooted, I could not unlock the screen at all. My home key brought up the passcode screen - but the touch interface no longer works so I cannot put in my code or swipe across the screen. The fingerprint detection no longer works either.

So, following advice on other forums, I have tried a hard refresh with the home and power buttons being held in for at least 10 secs. No change.

Plugged into iTunes for a restore on there. No change.

Tried the restore where you hold the home key and plug into iTunes to force recovery mode. Tried the recover option - still would not work.

Tried the recover and restore to previous backup option. Still would not work

Tried the recover back to factory settings. Still no joy.

Realised that the restore process wipes all your data (which I was warned about first), but it restores with the latest IOS system. Thinking that 8.3 was the root cause of the problem, I then carried out the process of backing out 8.3 back to 8.2.

Still nothing works.

Anyone have any pearls of wisdom before I go hunting down the nearest Apple Store? I am at my wits end - I have tried everything.

Thanks

iPad Air 2, 64Gb, wifi