What you describe sounds like a hardware failure (one where btrfs plays no specific role).
If that's indeed the case, you can only bring the drive to a data recovery service and see what they say (if it's a spinning disk, they'll probably recover the data for an exorbitant fee, if it's an SSD idk).
PS: this is unlikely to work, but.. you can try cleaning the drive's contacts to see if it makes any difference, and also try moving the drive to a different connector (or use it on another computer)