When batteries leak, they can corrode electronic components. I thoroughly clean the affected parts with a toothbrush and dishsoap. Depending on how far the chemicals have gotten, I may neutralize battery acid with baking soda. Both acid and alkaline battery chemistry can be neutralized with milk. This will bring it back to neutral ph. This gives peace of mind that the corrosion process is stopped.
Rinse well with water then with alcohol. Alcohol dries faster than water. Dry in front of a fan or hair drier. Reassemble. If there is no pressing need to use the device, allow to dry another day.