A. Unplug AC power from the wall for 30sec.  Check that there are no power to the chair by checking the front DCS (8) for no light.

B. Reset water level sensor by following the instruction below

Unplug AC power from the wall and reset water level sensor by following the instruction below

If the problem still persist. The Sensor might have problem. Replace the sensor  (10) (See Video Link)

If the problem still persist. The Sensor might have problem. Replace the sensor (See Video Link)