I would check the battery contacts on the gamegear to make sure that no other batteries have leaked already. If it does look like batteries have leaked in the gamegear before you are going to have to clean it all up. Have you tried to power the gamegear with an AC adapter? Usually you can pick up a universal adapter at Wal-mart for like $10 you just have to make sure it can do 9V.
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I would check the battery contacts on the gamegear to make sure that no other batteries have leaked already. If it does look like batteries have leaked in the gamegear before you are going to have to clean it all up.
Have you tried to power the gamegear with an AC adapter? Usually you can pick up a universal adapter at Wal-mart for like $10 you just have to make sure it can do 9V.