DIAGNOSIS The water level sensor float is stuck or the float arm is jammed. This is a common issue with mineral buildup.
FIX Unplug the brewer. Remove the water reservoir. Look inside the empty reservoir slot on the brewer base. You'll see a small white plastic float on a hinge. Gently move the float arm up and down several times. Use a cotton swab and white vinegar to clean any visible scale from the hinge and the well it sits in. Reinstall the reservoir.
IF THAT DIDN'T WORK The float sensor itself may have failed. This requires replacing the entire float switch assembly. You need part # DCB-300. It's a direct replacement for the DCC-3000. You must disassemble the brewer base to install it.
HEADS UP Do not force the float arm. It's brittle plastic. If you break it, you'll need the full replacement part. Always use filtered water to prevent this.