Honestly if one was concerned for the safety factor as a collectible, just remove the battery. Half of collectors don’t even play the games, just eliminate the problem and make a note of it. That’s why all my carts that I intend to keep, I’ve modified with a removable battery holder soldered in. I usually only play my carts once a year anyway and beat the game, then I can just remove the battery when I’m done. I’m not one to stress over a “save file”. Just start over and enjoy the game again.