dewalt chainsaw won't start at all, no noise, no click, nothing. battery works in my drill.

Diagnosis

When a DeWalt DCCS620B XR Chainsaw is completely unresponsive—meaning no LED indicator lights, no clicking from the relay, and no motor hum—the issue is almost always a break in the electrical continuity between the battery terminals and the motor controller. Since you have confirmed the battery works in another tool, the failure is isolated to the tool's internal power path or the safety interlocking system. The most common culprit is a failure in the electronic safety switch or a misalignment of the battery terminal pins. Because this tool handles high-current draws, the internal terminals can either oxidize or become slightly bent, preventing the "handshake" between the battery's BMS (Battery Management System) and the chainsaw's trigger assembly. If the tool doesn't even "click," the circuit is open, meaning the power isn't reaching the logic board. This can be caused by a blown internal fuse or a disconnected wire leading from the battery rail to the trigger switch, often caused by the vibration of heavy cutting.

How to Fix It

Follow these steps to restore power to the unit:

1. Inspect the Battery Rails: Remove the battery and look into the charging port of the chainsaw. Use a flashlight to check for bent copper pins or debris (like sawdust or wood chips) lodged in the terminal slots. Use a can of compressed air to blow out the port and a cotton swab with 90% isopropyl alcohol to clean the contacts.
2. Verify the Safety Lockout: The DCCS620B has a dual-action trigger. The safety lock (the lever on top of the handle) must be fully depressed before the trigger can engage the circuit. Ensure the lever isn't stuck in a "half-pressed" position due to debris; toggle it vigorously 10-15 times to clear any grit.
3. Perform a Hard Reset: Remove the battery. Hold the trigger and the safety lock down simultaneously for 30 seconds. This drains any residual capacitance in the motor controller. Reinsert the battery and attempt to start.
4. Check the Battery Seating: Ensure the battery is clicked fully into place. If the latch is loose, the battery may shift slightly during use, breaking the connection. Push the battery in firmly and ensure the locking mechanism engages with an audible click.

If That Didn't Work

• Test with a Different Voltage Battery: While your battery works in a drill, the DCCS620B is high-draw. If you are using a 2.0Ah battery, the tool may refuse to engage because the voltage drop is too high under the initial load. Try a 5.0Ah or higher XR battery to see if the tool triggers.
• Inspect for Internal Wire Fatigue: If the tool has been dropped or used heavily, the wires connecting the battery terminal block to the trigger switch may have snapped. If you are comfortable opening the housing, check for a loose solder joint or a disconnected spade connector on the trigger assembly.
• Check the Chain Brake Trigger: If the chain brake (the front hand guard) has been tripped, some versions of the electronic controller will prevent the motor from starting as a safety precaution. Pull the chain brake lever firmly back to the "off" position and ensure it is fully seated.
• Test the Trigger Switch Continuity: Using a multimeter set to ohms, check the trigger switch for continuity. If the switch shows an open circuit even when depressed, the trigger assembly (Part #D28481 or equivalent) has failed and requires replacement.

Heads Up

• Avoid Overloading: Never force the bar into the wood; let the chain speed do the work. Forcing the motor can trip the internal thermal overload protection, which may cause a temporary "dead" state until the tool cools.
• Chain Tensioning: Ensure your chain is not over-tightened. A chain that is too tight creates excessive friction, which increases the current draw and can lead to premature failure of the electronic controller.
• Battery Storage: Store your 20V Max batteries in a cool, dry place. Extreme heat can degrade the cells, leading to "phantom" charges where the battery works in a low-draw drill but fails in a high-draw chainsaw.
• Lubrication: Always check the bar oil reservoir before every use. Running the chain dry increases vibration and heat, which can loosen internal electrical connections over time.