Things You'll Need
Instructions
Lay your SNES game on a flat surface with the side the shows the screws facing up.
Unscrew the two screws from the game cartridge using either needle nose pliers or a hexagonal-shaped screwdriver. If you use needle nose pliers, you will need to place them inside of the screw and let them expand for a tight fit. Then turn the cartridge counterclockwise while holding the pliers in place until it is unscrewed.
Remove the cover from the game and locate the circuit board. The circuit board is green in color and rectangular in shape and it is the only removable piece inside of the cartridge. Remove the circuit board by lifting it away from the cartridge.
Turn the circuit board over and locate the battery at the top left corner of the game. The battery is silver in color, circular in shape, about the size of a nickel.
Remove the battery by lightly pressing a soldering iron to the legs on the back of the circuit board. You should be able to see two small legs that hold the battery into place. Pull the battery away from the circuit board while lightly soldering the legs off.
Bend the two legs on the new battery toward the positive side.
Cut the leg on the negative side of the battery to form a sharp point, two 60-degree angles.
Insert the new battery into the holes on the circuit board, with the negative leg going into the small hole and the positive leg going into the large hole.
Turn the circuit board over so that the battery is face down on a flat surface.
Solder the two legs with your soldering iron to hold the battery into place.