Can I chime in with one little thing that will help anyone buying an used DJI drone. With the drone in hand and seeing the serial number, use your phone and do DJI chat. U can ask the agent if the drone u r purchasing is binded to an account and...
In a way, I am glad DJI are sticking to their rules, as it could have been mine or another user's drone and sold without permission. You also say little to nothing about eBay, or if you tried using their refund process.