Remove the batteries
Wear gloves and eye protection
Check for leakage or heavy corrosion
Mix white vinegar or lemon juice for alkaline battery corrosion
Use rubbing alcohol for general cleaning
Apply the cleaner with a cotton swab or small brush
Gently scrub the contacts
Wipe away residue with a clean cloth or swab
Use a dry cotton swab to remove moisture
Let the contacts air-dry completely
Lightly scrape stubborn corrosion with a small non-metal tool or fine abrasive
Clean the battery compartment if needed
Insert fresh batteries only after everything is fully dry
Dispose of damaged batteries properly
Replace the device if the contacts are badly pitted or broken