Set Appliance State:

Ensure No demands are present
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Allow the boiler to complete its self-check.
If fault code is displayed, reset boiler.
Does the display show the boiler flow temperature?
Note:
1. If the boiler fault code changes from the original to a different fault code, then CLICK HERE.
2. If fault code is a recurring issue, then choose "boiler does not reset - fault code remains the same" to investigate possible causes.