Diagnosis
The toothbrush has lost power. The most likely cause is a drained or faulty AAA battery.
How to Fix It
Remove the metal refill head. Unscrew the bottom cap of the handle. Replace the included AAA battery. Ensure the positive (+) end faces the brush head. Reassemble. The brush should now function for its standard 2-minute timer cycle.
If That Didn't Work
Check for water ingress. Remove the battery and fully dry the compartment and battery contacts with a cotton swab. Reinsert a known-fresh battery. Corrosion on the contacts can break the circuit.
Heads Up
The Quip brush does not have a charging indicator. If it stops, assume the battery needs replacement. The motor is designed for the specific voltage of a standard alkaline AAA.