How to erase a previous iPTV Provide lock on mag250

I picked up a couple of used mag250 boxes however i cannot put in my private server info
is there a way to erase the previous provider info?
:mad:

If you bought stolen units from my store, I wish you luck. Return to factory settings is possible for me or assembly line of Infomir .
I'm happy with theft, insurer pay a better price than I expected to get from the sale of retail
 
Nothing was stolen
the guy bought a bunch of Mag 250 and was promises private service from some guy
the support stopped and the boxes are locked... Thats all that happened