my dewalt jigsaw just quit in the middle of a cut, no power or light at all. battery is charged.

Diagnosis

The complete loss of power and LED functionality on the DeWalt DCS334B typically indicates a total break in the electrical circuit between the battery cells and the motor controller. Because the tool stopped "in the middle of a cut," the most likely culprit is a momentary surge or vibration that caused a faulty connection to fail or triggered a safety disconnect. If the battery is confirmed charged via the charger's green LED, the issue is localized to the tool's interface or internal wiring. In many cases, this is caused by "contact creep" or debris infiltration. Fine sawdust from the cut can migrate into the battery rails, preventing the battery from seating deeply enough to engage the positive and negative terminals. Alternatively, if the tool experienced a significant kickback or jam right before it died, the internal thermal overload protector may have tripped, or a wire may have shaken loose from the trigger switch assembly. You can confirm a contact issue by attempting to slide the battery in and out rapidly several times; if the tool flickers to life for a split second, the problem is definitely the interface contacts.

How to Fix It

To restore power to your DCS334B, follow this precise cleaning and reseating sequence:

1. Remove the battery pack and inspect the gold-plated contact pins inside the tool's battery port. Look for "carbon scoring" (small black pits) or a film of sawdust.
2. Use a can of compressed air to blow out the battery cavity, focusing specifically on the recessed areas where the battery terminals lock in.
3. Take a cotton swab dipped in 90% Isopropyl alcohol and scrub the metal contact plates inside the tool. Avoid using water or soap, as this can lead to corrosion.
4. Inspect the battery terminals themselves. If you see a dull grey film on the metal, use a clean pencil eraser to gently scrub the contacts until they appear bright gold again.
5. Check the battery release latch. Ensure the spring-loaded button is fully extended and not jammed with debris, as this can prevent the battery from clicking fully into the locked position.
6. Insert the battery with a firm, decisive push until you hear a loud, audible click. Apply slight pressure to the battery while pulling the trigger to see if the connection is intermittent.

If That Didn't Work

• Swap Battery Platforms: Test the tool with a different 20V Max battery. Even if the charger says "charged," a single dead cell within a specific pack can trigger the tool's internal Low Voltage Cut-off (LVC), which prevents the motor from turning on to protect the battery from deep discharge.
• Check for Trigger Jam: Inspect the trigger switch for sawdust buildup. If the switch is stuck in a "half-pressed" state or is clogged with debris, the tool may not register a clean "on" signal. Use a thin needle or compressed air to clear the gap around the trigger.
• Reset Thermal Overload: If the tool was running hot before it quit, the internal thermal switch may have opened. Leave the tool unplugged from the battery in a cool environment for 30 to 60 minutes. Do not attempt to force it to run; let the bimetallic strip cool naturally.
• Inspect Internal Wiring: If you are comfortable removing the housing, open the chassis and check the wires leading from the battery terminals to the trigger switch. The DCS334B is subject to high vibration, which can occasionally loosen the spade connectors on the trigger assembly. Ensure all wires are firmly crimped.

Heads Up

• Avoid using WD-40 or oily lubricants on the battery contacts; this attracts sawdust and creates a conductive "sludge" that can cause short circuits or overheating.
• Always remove the battery before changing blades or performing maintenance to prevent accidental trigger activation.
• Periodically blow out the motor vents with compressed air every 10-15 hours of use to prevent the thermal overload from tripping during heavy rip cuts.
• Ensure you are using genuine DeWalt 20V Max batteries; third-party "knock-off" batteries often have slightly different terminal dimensions that lead to the exact power-loss issue described here.