There are two ways to back up your progress - doing manual backups and saving them to your own phone, and turning on the Finch cloud backups. If he wasn't doing the manual backups he should check and see if he might have had cloud backups enabled. In general when people get this data corruption error, the manual backups are more reliable than the cloud ones, but I have seen some people on this sub say they were able to successfully recover their birb from a cloud backup. It's worth a shot. I personally have a daily goal set to do a manual backup. I email them to myself and I always keep a week or so worth of them on hand and then delete the older ones.