A common mistake is that the leak is ACID, it is infact an alkaline: Potassium Hydroxide. This is a corrosive base. The way to neutralize the leakage, after removing the battery, is to wash the affected area with a solution containing a 50/50 mixture of (white) vinegar and pure distilled/deionised water. Scrub carefully with an old toothbrush, and then rinse with pure water and force dry with a hair dryer on low.