If they were the typical lead acid dry cells (the cheap non alkaliine or metal something or other type) then baking soda will be the choice to clean it out, if its an alkaline or mn type pbattery then white vinegar would be the best. should not be a need to scrub with a wire brush, just apply the liquid with a swab and keep swabbing until all corrosion is dissolved. Follow up with distilled (RODI) would be gresat to remove any traces of liquid used to clean it, once dry follow up with a light buffing of the contact springs and clips with a pencil eraser or such, make sure its totally dry and use it. Just make sur eyou do not flood it and allow liquid to get into the elctronics portion of control.
You need to use a acid based compound for alkaline battery leakage and alkaline base compound for acid based battery liquid....