YouTube user MufasaAM has put together a video to demonstrate how to replace a battery in a Game Boy or Game Boy Color game. In this case, he replaces the battery of the Pokémon Crystal cartridge. This process requires opening up the cartridge, so be prepared to work with the proper tools. To watch the entire how-to-tutorial, check out the video below:
Video: How to replace Game Boy and Game Boy Color batteries featuring Pokémon Crystal
Pokémon Blog 