DIAGNOSIS A flashing red light on the base indicates a charging error. This is almost always a connection issue between the robot's metal contacts and the base's pins.
FIX Unplug the base. Check the two metal pins on the base's charging ramp—wipe them with a dry cloth. Then, check the three metal charging contacts on the underside of the robot. Clean them with a dry cloth or a cotton swab. Make sure there's no debris on the ramp. Replug the base and carefully re-dock the robot, listening for the confirmatory beep.
IF THAT DIDN'T WORK The robot's battery might be completely dead and unresponsive. Leave the robot manually seated on the contacts for at least 6 hours. If it still shows no signs of life, the battery may need replacement.
HEADS UP If you use cleaning sprays on floors and the robot drives through them, residue can get on the contacts and cause this. Always clean with a dry cloth.