There should be icky white flakey material all over which is the battery acid, and greenish stuff coating the wires.
Well, no. The leaking electrolyte is highly corrosive but it's not an acid. It is a base. A3000s came from the factory with nickel-cadmium batteries. The commonly used electrolyte for NiCd batteries is potassium hydroxide.
Folks use baking soda diluted in water with a toothbrush to give the damaged area a good scrub.
If you're using the baking soda to neutralize the "battery acid" then that is useless. You would have to use a weak acid instead such as diluted vinegar.
