I have refurbished a dozen gameboys or so. I have never found one to have leaky caps or noticeable damage other than lines in the screen and battery acid on the contacts. mixing and matching the two internal boards, if you have a few gameboys on hand, can give you a working machine if one board is zapped. Putting a thin piece of foam tape at the base of the lcd were the contacts are can help remove lines when the machine is reassembled. battery acid can easily be removed with a mixture of baking soda and water. thats the best i know. board level troubleshooting would be the next step after that i imagine, and thats outta my league.