Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Gas Off
DHW Demand
Disconnect spark electrode lead from the igniter unit
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Press reset to cancel purge cycle countdown.
STAND CLEAR OF THE APPLIANCE.
Allow fan to run and ignition sequence to commence.
Can sparking be seen between the spade terminal on the igniter and the heat exchanger support bracket to the left?