Just a gloss on part of Dieter's excellent advice:
Then, you could try "fsrecover" to get part of your "Data.fs" back (about 475 MB).
Derek's .fs file is over 5GB. People tend to believe that fsrecover.py truncates a damaged .fs, but that's just because most people run it immediately after a power outage, or other circumstance in which just the tail end of the .fs is damaged. Then fsrecover does truncate it. But fsrecover *tries* to be smarter than that: it looks ahead after each damaged area it finds, for the first place it can "synch up" again. So it's possible that fsrecover will recover nearly the entire 5GB here; it's also possible that it will only recover 475MB.
You probably will loose some data.
That's certain, since fsrecover works by throwing bytes away. What's impossible to guess is whether it will throw away anything the app still needs. If the app is running is OK, the odds of success are decent.