How do I get battery acid corrosion of the board?

Brandon Coleman just as suggested by Russ Walden. First remember that your batteries are alkaline not acidic. Alkalinity is just as corrosive as acidity but to clean it you will need the acidity. I use a 50/50 mix of vinegar and sterile water. It is okay to place the whole board in that solution. Use a small soft brush to gently scrub the residue of the board. Once it is properly cleaned, rinse it of with sterile water. Then clean the board with 90%+ isopropyl alcohol to displace all the water. Looking at the schematic, your GameBoy should work with just an AC adapter. If you post some images of your circuit board and the damage, I am sure we can give you a better idea on how to fix it.