Flashlight won't turn on

Symptoms

• No light at all when the switch is pressed
• Flashlight worked recently and now nothing
• Switch feels loose or doesn't click
• Flickers briefly then goes dark

Likely causes

• CommonDead batteriesBatteries are by far the most common cause of a flashlight not working.
• CommonCorroded battery contactsOld batteries can leak and corrode the metal contacts, breaking the circuit.
• PossibleBatteries inserted with wrong polarityReversed batteries won't complete the circuit.
• PossibleFaulty or stuck switchSwitches wear out or can get gunked up with dirt over years.
• Less commonBurned-out bulb (non-LED flashlights)Incandescent bulbs eventually burn out like any light bulb.

What to do

1. Remove the batteries and check the printed polarity markings inside the battery compartment against how they're inserted.
2. Test with a fresh, known-good set of batteries of the correct size.
3. Look at the metal contacts (spring and flat contact) for white or greenish corrosion.
4. If corroded, scrape gently with a small flathead screwdriver or fine sandpaper, or clean with a cotton swab dipped in vinegar or lemon juice, then dry thoroughly.
5. Wiggle the switch and press it firmly a few times to see if it's just sticky; a drop of electronics-safe contact cleaner can help.
6. If it's an older bulb-type flashlight, check whether the bulb has a visibly broken filament and replace it if so.

Tools and parts

• Small screwdriver
• Fine sandpaper or cotton swab
• Vinegar or contact cleaner

When to call a pro

Flashlights are rarely worth professional repair; if cleaning contacts and fresh batteries don't help, replacement is usually cheaper.

Safety