The new Playstation release, Helldivers, seems to be having a bit of trouble. According to Kotaku, players have been reporting odd bugs that will wipe all progress if the batteries in the controller die. Apparently, the glitch will cause a new level one character to spawn and immediately save over your previous data -- effectively wiping your save.
Helldivers developers, Arrowhead, have confirmed that this is an issue and that they will be working on fixing for the forthcoming 1.03 patch. In the meantime, Arrowhead posted a few tips on the Helldivers subreddit.
Wiped progression? Don't turn off your controller!
There is currently an issue with players experiencing wiped save data. We found an issue related to the controller dropping its connection to the game and then when you reconnect, the game spawns your avatar before it manages to load your old save. This results in what looks like lost progress, and often results in progress being lost if you let the game finish its save.
What we are doing about it: We have fixed this specific occurrence and are investigating other ways that save data might get reset as we are seeing reports of unrelated save reset issues. The fix for this specific issue will be in patch 1.03.
What you can do about it: Make sure your controller has a full charge when you start playing. Don't switch controllers if you battery is running low, just connect it to a cable, and wait until you are on the bridge and done with saving before switching to another controller.
If this issue should occur, restarting the game without saving will cause it to try and download the cloud save next time you start it up. This may solve the issue, but will not work if you have managed to save since you got reset.
This bug isn't the only one plaguing Helldivers players right now, though. On the Playstation forums, users of PS4 and PS Vita versions of the game have been reporting all kinds of issues with transferring saves and problems with online multiplayer. Obviously not all of these are caused by a dead controller battery, and there's been no word on if they’ll be addressed in the new update.