Set Appliance State:

Mains Power Off
On/Off Switch OFF
DHW Demand - Ensure Store is not up to Temperature
Gas On
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Appliance On/Off switch On.
Reset lock out as necessary.
Allow fan to run and burner to ignite.
Does the hot water storage cylinder reach a satisfactory temperature?