I purchased a PV2 from a friend (he's upgrading to the PV2+). I tried to register it on DJI's web site. When I put in the serial number I got the message "Sorry, the code you entered has been registered by others". Obviously he already registered it. I was able to register the remote. After registration I saw no way to unregister it so my friend will most likely have the same problem trying to unregister the copter. I tried calling DJI with no success. Has anyone else had this issue?