I have encountered a situation wherein I did not remove the old JAMF MDM from a iPad prior to rebuilding the database (Corruption error) with a new MDM and everything.
These old devices when a co-worker did a reset on them indicates it cannot contact the MDM server.
Are they Bricked?
This sounds similar to the issue I am going to encounter soon as I have to change the URL of my server to match our new domain.
From what I'm told the MDM won't autoupdate on iPads, (They will on macs its seems though). So I will literally have to touch each and every iPad once again, or right before the url change I'll have to make sure all iPads are part of a pre stage enroll, then issue a wipe command, then change the url and they will get the new mdm. Really quite a pain in the ass considering we have close to 2000 iPads.
Not sure if this helps you though lol....sorry.
Princeton Public Schools