Replace your Batteries! Not only will this restore the save function but will preserve your games. As game batteries age they will eventually leak on the motherboard and cause damage.
Batteries are easy to replace if you have basic soldering skills. This battery CR1616 is the exact size of battery used in most gameboy games. Many tutorials can be found online
Tools needed to open most Gameboys:
3.8mm Bit (sold in my store)
Solder and Iron (skill required)
We offer install service for batteries if needed. Check our other store listings for more info.