At first I discovered saves disappear after resetting the game. I tried to remember if there was any trick about saving but couldn't find the game manual. Then I suspected there may be something about battery. I opened the cart and saw whole the inside was messed up and covered with green yeasty stuff. Battery has been run empty and then have started leaking.
I cleaned it with care, used alcohol to melt the green stuff. Then I started removing leaking battery. Those batteries are some sort of pain to replace because the connectors are riveted to battery. So there are two ways for that. One is by soldering the connectors off directly from board of game cart or just by tearing the rivets off the battery. I chose the last way as soldering may harm the board.
Now I have to figure out how to fasten the replacement battery. Those connectors are not clips as we used to and battery must be riveted again somehow. Soldering do not work on batteries very well, maybe I should use hot glue.
I wonder if all those cartridge batteries explode when they run out of charge. It would be huge mess if someones full collection of Super Nintendo games will start leaking one day
