I asked DJI this a while back. They answered me in Chinese with what I believe was a cut and paste stock response.
I then got transferred to the N/A contact and got the follow:
Mai (DJI)
Aug 7, 03:21 HKT
Dear Mike,
Thank you for contacting DJI Customer Support.
Mike, we can only register the unit to us once. Since you are the second owner you won't be able to change the registration or register it under your account.
The thing that you can change is the log in ID on the DJI GO APP.
The registration process happens after purchasing the drone and the first owner already did that. Registration process is only done once in every unit.
Hope this will help!
If you have any other inquiry in the future please feel free to contact us back anytime and we will be more than happy to assist you with your concern.
Have a wonderful day ahead.
Best Regards,
Myra