Clarify.
Sounds like you have it bound to your account (since you've been using it), now you sold it and the new owner is saying it's bound to another account.
I.e. you have to go into the DJI Fly app and remove the drone from your account so...
@iAmJD,
"I bought it brand new and I used it occasionally for a year until I decided to sell to someone. But to my surprise the Drone was "already bound to another account""
So, You never had bound it?
Rod .
This posting will explain that nothing will happen for you now and why... But as others have pointed out, what is the rest of the story?
https://mavicpilots.com/threads/notice-to-all-pilots-that-plan-on-buying-a-used-dji-drone%E2%80%A6.152382/