my dewalt dcr600b router just flashes the battery light and won't spin up, even with a fresh pack.

Diagnosis

The flashing battery indicator on the DeWalt DCW600B is not actually reporting a low battery; instead, it is a diagnostic code from the brushless motor controller indicating a "Protection Lockout" state. This occurs when the Electronic Control Unit (ECU) detects a critical anomaly—such as an over-current spike, a thermal overload, or a signal mismatch from the trigger—and shuts down the motor to prevent the MOSFETs from frying. In most cases, this is triggered by carbon dust or sawdust infiltrating the trigger switch assembly. Because the DCW600B is used for routing, fine particulate matter often bypasses the housing seals and settles into the switch contacts. This creates intermittent resistance or a "ghost" signal that the controller interprets as a short circuit, triggering the safety lockout. You can confirm this if the light flashes immediately upon trigger pull, even without a bit installed, or if the tool occasionally works after a hard shake of the handle. If the lockout persists with a known-good 5.0Ah or 6.0Ah battery pack, the issue is likely a logic hang in the controller or a physical failure in the switch's internal spring mechanism, preventing a clean "on" signal from reaching the PCB.

How to Fix It

To resolve the lockout and clean the internal contacts, follow these precise steps:

1. Remove the battery pack immediately to kill all power to the logic board.
2. Perform a "Hard Reset": Press and hold the trigger switch firmly for 15 full seconds. This drains the remaining capacitance in the motor controller and clears the temporary error state.
3. Remove the three T15 Torx screws securing the rubberized handle grip and the plastic housing of the upper assembly.
4. Carefully lift the housing to expose the trigger switch and the wiring harness. Locate the switch terminals where the wires connect to the PCB.
5. Apply a high-quality non-residue electrical contact cleaner (such as DeoxIT or CRC QD Contact Cleaner) directly into the crevices of the trigger switch mechanism.
6. Actuate the trigger 20-30 times rapidly to work the cleaner into the contacts and scrub away any embedded sawdust or carbon buildup.
7. Use a can of compressed air to blow out any remaining debris from the switch area and the ventilation ports of the motor housing.
8. Reassemble the housing, ensuring the wires are tucked away from the pinch points of the casing, and reinstall the battery.

If That Didn't Work

• Test with a Different Battery Voltage: Ensure you are using a 20V Max XR battery. If you are using an older, non-XR pack, the voltage drop during the initial "spin-up" surge may be triggering the low-voltage cutoff, which manifests as a flashing light. Swap to a high-output 5.0Ah pack to rule out amperage sag.
• Inspect the Collet and Bit: If the bit is jammed or the collet is over-tightened/seized, the motor may be detecting an "instant stall" (locked rotor). Remove the bit entirely and attempt to start the router. If it spins without a bit, the issue is mechanical resistance in your workpiece or a bent shank.
• Check for Internal Wire Chafing: Inspect the wires leading from the trigger to the main board. Look for any pinched insulation or exposed copper. A momentary short to the metal chassis will trigger the protection lockout immediately.
• Replace the Trigger Switch Assembly: If cleaning fails, the internal micro-switch has likely failed mechanically. Order a replacement trigger assembly specific to the DCW600B model and replace the entire switch unit.

Heads Up

• Dust Management: Always use a vacuum attachment when routing hardwoods; the fine dust from oaks and maples is particularly conductive and prone to causing these electronic failures.
• Battery Heat: If the battery light flashes during a long routing session, it is likely a thermal shutdown. Let the battery cool for 15 minutes before attempting to restart.
• Avoid Lubricants: Never use WD-40 or oil-based lubricants on the trigger switch, as these attract sawdust and create a thick sludge that will permanently jam the switch.
• Collet Care: Periodically clean the collet threads with a nylon brush to ensure the motor isn't fighting unnecessary friction during start-up.