Set Appliance State:

Mains Power Off
Turn Hot Water Tap On
Boiler On
Set SUMMER/WINTER switch to the SUMMER position
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Control panel lights - demand and HW minimum temperature LEDs.
Did the DEMAND LED (Yellow) and the HW Minimum Temperature LED (Green) come on?