Diagnosis
A fast-flashing white light indicates a critical battery or system error. The brush is in a fail-safe state.
How to Fix It
1. Place the handle on its charger immediately.
2. Leave it connected for a full 24 hours, uninterrupted.
3. Do not press the power button during this time.
4. After 24 hours, remove it from the charger. Press and hold the power button for 10 seconds to force a reset.
5. Return it to the charger. It should now show a normal charging light (flashing or solid white).
If That Didn't Work
The lithium-ion battery has likely failed beyond recovery. This error state is often terminal. No user-serviceable parts exist inside the sealed handle.
Heads Up
This error can be triggered by allowing the battery to fully discharge and remain dead for several months. For long-term storage, leave the brush with a partial charge (50%) and not on the charger.