Set Appliance State:

WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

This fault situation can often be remedied by performing a hard reset of the PCB:
Reset appliance by holding reset button in for 5 seconds then releasing
Activate Service Mode (Chimney Sweep)
FOR INFORMATION ON ACTIVATING SERVICE MODE CLICK HERE
Allow appliance to run for 30 seconds
Deactivate Service Mode (Chimney Sweep)
Perform the above steps twice more so the boiler has been put into and taken out of service mode 3 times in total.