Set Appliance State:

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

Observation:

Press the "i" button once.
After the burner has ignited and established the boiler should show "S.4" to indicate normal operation.
Monitor the appliance for at least 2 minutes.
Does the boiler remain on status S.4 or does it show S.53 / S.54 indicating a circulation issue.
Note:
If the boiler extinguishes it will show S.5 / S.6 / S.7 or S.8. If this happens select "Boiler does not indicate a circulation issue"