Xbox Fallen order, not working. *Sadness*

Not sure what happened. Xbox was having problems with the Disc Drive, did a factory reset. Fallen Order was a download Xmas gift to husband, it was saved the the external Hard drive. The external drive was disconnected at the time of factory reset. was able to download, or copy to Xbox, but unable to play the game. I have the product key, but that's no use now as it says it's been used, (even for the same account).

Help me Obi Juan, you're my only hope.