Just to complete this thread that I started couple of weeks ago, the USED
mini 3 pro drone that came from this unfamiliar internet company turned out to be broken from the get go. Since I had paid through Amazon Pay (which guarantees customer satisfaction through their A-Z warranty program), the return was not that difficult. Shared couple of pictures of the broken drone with the customer service rep, and I was able to return the drone for a full refund.
A few days later I got a used DJI RC remote from Amazon, and a refurbished
mini 3 pro from DJI. They both connected fine, and and DJI
mini 3 pro is now successfully bound to and connected to my account. Ended up buying DJI care refresh too. So all good here. Didn't save much money. But I have a second pair of drone now to complement my
Mavic 3!