Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Water OFF
Drain off excess water through hot tap

Observation:

Inspect the flow regulator/filter for blockages or damage.
Note:
Flow regulator/filter is located on the DHW inlet isolating valve. The filter restrictor can only be removed when the isolator valve is in the fully off position (slot across the valve) - the filter will be damaged if removal is attempted with valve not in the fully closed position.