Common household alkaline batteries are subject to leaking under certain conditions. In some cases, the leaking batteries are still providing power to the electronic device. The residue that leaks out of a battery and onto the contacts dries into crystals that interfere with power distribution. Battery leakage causes irreversible damage to electronic circuit boards. There is a way to clean up the residue from leaking alkaline batteries on the inside of battery cases and repair the damage to battery contacts. Then a fresh set of batteries will restore power.
Put on rubber gloves and safety glasses before touching the device with battery leakage. The residue causes skin and eye irritations.
Remove the leaking batteries from the device. Take out any batteries that are not leaking as well and dispose of all batteries from the device.
Dip a cotton swab into lemon juice or vinegar. The acid neutralises leakage from alkaline batteries. Rub the moistened swab over all sections of the battery case that have liquid or crystallised residue. Wet the affected parts with enough acidic solution to loosen all the residue and dry the parts with a paper towel.
Sand the metal battery contacts with fine sandpaper. Wrap the sandpaper around a Popsicle stick, or over the end of a slotted screwdriver and sand inside bent contacts and between spring coils on battery contacts. Clean sanded parts with acidic solution and wipe dry.
Replace all circuit boards exposed to leaking alkaline batteries. Even some flashlights have small circuit boards. Contact the battery manufacturer for information on warranties against damages from leaking batteries (see Resources). In some cases, manufacturers will replace items damaged by their batteries.