I looked at the battery of the 3 in 1, I'm no expert in electronics, but it lloks similar to the battery of a gameboy color
game I have, maybe someone who understands in this stuff would know if we can use the battery from an original gbc
(or any other gba game) with the 3 in 1
YOu can most likely buy the battery in an electronics store (or even a general store...really anywhere that sells Watch Batteries) It's the whole replaceing part that might be a bitch. I'm not sure since I haven't taken my 3 in 1 apart, and I'm not sure weather the battery is soldered on, or just clipped on. (It'd be great if it was simply clipped on.