Yeah, There is a lithium-ion battery soldered onto the circuit board inside of certain cartridges that have programs that require saved data (what level your up to) like Super Mario World, Mario cart etc. I had to order the battery and a tool to unscrew those funny screws that nintendo uses to seal their cartridges with. Once I fix it, it should be good for another 20 years or so. This youtube video shows what I will have to do to fix the problem. YouTube - How to Replace a SNES Game Battery Looks pretty easy to do.
I believe it is something like that CMOS battery in our motherboards. The contents might be inside the RAM of the board and retained by the small power of the battery. Could it be?
Great work. We all love retro consoles. Btw, I can hazard a guess here - the small Nintendo chip in the board could be that region check thing?
I'm back on 'The Donut Plains 2'. YouTube - Let's Play Super Mario World - #2. The Great Donut Frontier