Regarding firmware 'known issues'. The only thing I'm aware of (from personal experience) is that firmware .0670 increased the control signal strength and either .0770 or .0772 dropped it back down again, but also provoked a series of glitches in...
There is a painfully simple solution to this situation.
You say that during the sale, you and the dealer went outside to test fly the drone... yes? That would explain why it is bound to another account.
Take it back to the individual who sold...