iPad stuck in verifying update after having been my beta test device

Hi!

I‘ve used my old iPad Pro as my iOS 15 beta test device. With one of the latest beta releases the device showed the behavior that it never completed the „Verifying update“ step.

With the official release of iOS 15 I used a desktop connection to restore the device to the official iOS 15 release.

However, the 15.0.2 release of today is again stuck in the „Verifying update“ step.

What could be the problem here? I thought restoring the device will reset the device to factory settings? Other iOS devices on my network update without my issues. It‘s just this beta test device that‘s making problems.

Christian