-Clear all settings - Didn't help
-Recovery Mode refresh of the OS. Recovery went fine, but crashes every 2-3 minutes during setup and then during operation. (no apps or backup restored)
-Reset to factory - crashes every 2-3 minutes during setup and then during operation. (no apps or backup restored)
-Reset to factory and then a recovery mode load of the OS. Recovery went fine, but crashes every 2-3 minutes during setup and then during operation. (no apps or backup restored)
-Try to downgrade to 13.7 - Keeps crashing during the process and can't get the OS onto the device. Now it's apparently no longer being signed
-Tried completely draining the batteries and recharging
Tried leaving the device in recovery mode. Does not reboot until the actual recovery mode timeout.
I did contact Apple support and it's a flat $599 swap fee. The device was fine before the iOS upgrades and the theory they have is that it "highlighted an existing hardware issue". (not to be confused with "we didn't really do extensive testing with legacy hardware and you should have upgraded by now anyways")
Apple could make a fortune offering paid downgrade services. I'd be a lot more willing to pay for a 13.3.1 downgrade and version freeze than $600 for the same device that's just waiting for a future upgrade to "highlight" another hardware issue.
I guess it goes in a drawer and comes out for testing with each new iOS version until the official EOL.
This is probably the push I needed to get rid of the iPad altogether. The only business apps I was using on it were Microsoft, so it was getting harder to justify (and the games on the app store were draining my wallet). Maybe not a silver lining, but maybe a tin one.