4th Gen iPad Pro - MDM Removal Issue

I've got a problem with removing MDM from my iPad Pro (4th Gen). I logged into the Apple Business Manager, removed the device, then I did a factory reset on the iPad. I then removed the MDM profile and server details from our MDM policy system, JumpCloud, completely.

It's factory reset, but it didn't remove the MDM from the iPad. Now, it still says the company name and "Enrol Now", but whilst the popup appears, it's just blank and I can't go anywhere or do anything. I've tried a reset of the iPad (to go back to the beginning of the new device wizard), but still the same. Seems impossible to get past it.

Any ideas what to do next please? I no longer use this iPad Pro, which is the reason for removing the MDM, as I'd like to sell it.