Very large organizations like Verizon likely have their devices enrolled from the factory, it could be new but it's likely stolen, innocently mixed up as a retail product for sale or liquidated to a 3rd party as "new old stock" (unlikely IMO).  However, generally speaking, when you see this screen, it's usually not “brand new in the box” as you describe.  The fact that it had [MDM installed/enabled][1] (manual process) means at a minimum, it was configured for use.  The moment that happens, it’s no longer "new" but "used" (pre-owned) or at the very least it's considered "Open Box." 

The problem here is that you could have something that is legitimately sold from Verizon to the third party via liquidation and the MDM was innocently overlooked to it being a stolen device in which case, if you are in possession of it, you could have it confiscated by authorities without compensation back to you. 

In this particular case, Verizon being a large company with a large bureaucracy, it will be a Herculean effort to validate its legitimacy  and to get MDM removed.  I would return this to the person you purchased this from for a full refund as it’s not as described - brand new. Let the vendor deal with removing the MDM - this is the "value add" he's supposed to provide.

This is not to say that buying from 3rd parties is to be discouraged; you just have to be more diligent. Here are some tips for dealing with 3rd parties:

* Use a service that offers purchase protection like PayPal or eBay
* Test it out; boot it up and test before closing the deal. If you run into this type of error, walk away. 

* Boot it from a completely off state.  If the machine is running and “waiting” for you, it could be a sign of trying to obfuscate issues. Shut it down completely and boot from off. For instance, they may have booted into Safe Mode, obscuring any issue that might occur during a normal boot

* Test everything while on battery.  

  * There are keyboard test sites (https://www.keyboardtester.com/)  or you can use [Karabiner Elements][2] (it has an event viewer) this will help you ensure the keyboard is good (You can also try [`xev`][3] but it requires XQuartz to be installed (both are free)
  * [Memtest86][4] is free and you can boot it off a USB drive
  * [DriveDx][5] is free for diagnostics (pay for data recovery) and is an excellent tool to test out the storage

* Check the battery stats.  [You can do this from Terminal][6] without extra software.  Issue the command:

      $ system_profiler SPPowerDataType | grep -i "charge information" -A 10

  See the link for sample output.  If it's brand new it won't have a bunch of cycles (should be in the single digits) and the "max charge" and "charge remaining" shouldn't have much of a delta if the battery's fully charged.

* (I can't stress this enough) **If this is an in-person transaction, do this at a police station.**  Some even offer a well lit, camera monitored space in the the front parking lot to do the exchange.  If your seller balks at this, you'll know something's not right and should walk from the deal.

### Conclusion

Most of all, live by the philosophy caveat emptor or buyer beware. If a deal seems too good to be true, it probably is. If you not "strong" in tech, do what you'd do if buying a used car from a 3rd party - bring along a tech to give you the thumbs up/down on the purchase.   


  [1]: https://www.apple.com/business/docs/site/DEP_Guide.pdf
  [2]: https://github.com/pqrs-org/Karabiner-Elements
  [3]: https://apple.stackexchange.com/a/317556/119271
  [4]: https://www.memtest86.com/
  [5]: https://binaryfruit.com/drivedx
  [6]: https://apple.stackexchange.com/a/328981/119271