The battery or charger has a fault. The red flash is an error indicator.
- Confirm the charger is plugged into a working outlet.
- Unplug the charger. Remove the battery from the mower.
- Inspect the battery terminals and the charger terminals for dirt, grass, or corrosion. Clean with a dry cloth if needed.
- Reconnect the battery to the charger firmly. A solid red light should indicate charging. A flashing red light persists if there is a problem.
IF THAT DIDN'T WORK: The battery may be too hot or too cold. Let it sit at room temperature (approx. 65°F - 75°F) for an hour, then try charging again. If it still flashes red, the battery or charger may be defective.
HEADS UP: Only use Greenworks 40V chargers. Do not charge a battery that is physically damaged, leaking, or has been immersed in water.