Set Appliance State:

Mains Power Off
Ensure NO demands
Selector switch in Heating & Hot Water position
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Does the Power On LED illuminate?
Wait at least 10 seconds after mains
power on to confirm that the pump
does not attempt to run without
any demand for DHW or CH.