Naomi MvC2 Unlocks

Just curious about how MvC2 character unlocks are handled with Naomi? I bought a MvC2 cart recently and used the service mode codes to unlock all of the characters. Anyways, it's been a few weeks since I turned it on, so I went and turned my cab on today to play and my Exp and characters were all gone. Does the Naomi need to be powered regularly to keep the characters, or am I just an idiot and did something wrong?

It should keep them unless you remove the cartridge, if you didn't remove the cartridge then you probably need to replace the motherboard battery.

Put a new CR2023 battery on the board.

heh Didn't realize it was that simple. Thanks guys.