Alkaline batteries can leak and start a corrosive process. When this occur it start to damage all metal parts of the circuits if you don’t stop it in time.

The corrosive agent is potassium hydroxide and an easy way to clean up this is using common vinegar. Only submerge it on a glass with vinegar and shake it every X minutes [I shake it when I remember that I've a glass with vinegar near my computer :) ].

Cleanning with Vinegar Alkaline Battery leak

Cleanning with Vinegar