my dewalt 20v chainsaw ran fine yesterday but today it just clicks when i pull the trigger, no blade movement at all.

Diagnosis

The rhythmic "click" you hear when pulling the trigger on the DeWalt DCCS620B is the sound of the motor attempting to engage while the mechanical chain brake is locked. This is not an electrical failure or a blown fuse; it is a safety mechanism designed to prevent "kickback" injuries. When the chain brake is engaged, a steel band physically clamps the sprocket, preventing the chain from rotating even if the motor is receiving power. This often happens inadvertently during transport or if the front handguard was bumped while setting the tool down. Because the motor is brushless and high-torque, it will try to force the chain to move, but the mechanical lock prevents it, resulting in that distinct clicking sound as the electronic controller detects the resistance and cuts power to prevent the motor from burning out. You can confirm this by checking the position of the front handguard; if it is pushed forward (away from the handle), the brake is active.

How to Fix It

To disengage the brake and restore chain movement, follow these precise steps:

1. Remove the 20V Max battery from the tool entirely to ensure there is no accidental activation during the process.
2. Locate the front handguard (the large plastic shield situated in front of the left-hand grip).
3. Grip the edge of the handguard firmly and pull it backward toward the rear handle in one swift, decisive motion.
4. Continue pulling until you hear a loud, audible "click" and the guard locks into the rearward position. This unlocks the sprocket clamp.
5. Reinsert your 20V Max battery, ensuring it clicks firmly into the rails.
6. Squeeze the trigger fully. The chain should now rotate freely without the clicking sound.

If That Didn't Work

• Check for Chain Jamming: If the brake is disengaged but you still hear clicking, the chain may be pinched or derailed. Loosen the bar nuts using the onboard tool, remove the guide bar, and inspect the drive sprocket for any wood chips or debris wedged between the sprocket and the housing. Clear any debris with compressed air.
• Battery Voltage Threshold: The DCCS620B requires a high current draw to break the initial inertia of the chain. If you are using a low-capacity battery (e.g., 2.0Ah) that is nearly depleted, the tool may "click" as the Battery Management System (BMS) trips the over-current protection. Swap to a fully charged 5.0Ah or 9.0Ah XR battery to see if the problem persists.
• Inspect the Trigger Safety Lock: Ensure the safety lock-off button (the sliding switch above the trigger) is fully depressed. If the switch is partially engaged, it can cause erratic electrical contact that sounds like a rapid click or stutter.
• Verify Chain Tension: An over-tightened chain creates immense friction on the motor. If the chain is too tight to move by hand (while the tool is off), the motor will stall immediately upon startup, creating a clicking sound. Loosen the tensioner screw and ensure there is a slight "sag" in the chain.

Heads Up

• Chain Lubrication: Never run the DCCS620B without checking the bar oil reservoir. A dry chain increases friction and heat, which can lead to the motor overheating and triggering an automatic electronic shutdown.
• Battery Heat: If the battery is too hot from a previous task, the XR circuitry will prevent the motor from engaging to protect the cells. Let the battery cool for 15 minutes if you notice a sudden loss of power.
• Cleaning the Sprocket: Every 5-10 cuts, use a stiff brush to remove sawdust and oil buildup from the drive sprocket area. Accumulated grime can interfere with the chain brake's ability to reset fully.
• Tension Check: Always check chain tension after the first 5 minutes of use; the chain stretches as it warms up, and improper tension can lead to the "clicking" stall you experienced.