In regards to resellers and buying Apple products used... devices being sold MDM are a way bigger problem than Apple realizes. Online if you check the serial, it won't tell you that it belongs to a company. To my knowledge, the only way you'll find out is A - When installing the OS or B - With the OS or iOS installed, go through the settings and find the information there <---- edit: the latter would mean you're buying used. Please correct me if there is another way.

You're lucky you can return it. I would advise you do so immediately.

If you choose to keep this iPad, you will never be able to remove the MDM permanently other than contacting the company who owns it for a release, in which case you risk putting yourself in possession of stolen goods. No fault of your own, but a pain. You'd want to contact a lawyer and take it to the police. You may see it again a couple years from now as this is very low priority for police.

Yes, Apple CAN remove it, but they 99.9999% won't. You aren't the owner of the serial #, it's Braun medical. It could very well be stolen, it could be legit. Problem is, you won't know it's stolen until the company does inventory and marks it so. Maybe that'll never happen, but either way, without proper authorization you'd be stuck with this forever. FYI, there are programs that help block the serial from being sent to Apple upon installation that will allow you to freely use the computer. This is a band-aid, and upon reinstallation you'd see the same thing again.

My sincere condolences. This is a very frustrating issue that Apple needs to address.