Set Appliance State:

Allow fan overrun to commence
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

The fan will overrun to cool the heat exchanger down, this can take up to 30 minutes according to the manufacturer.
Note:
If the fan does not overrun or you do not want to wait the 30 minutes, you can cool the appliance by draining off some water, then topping the system pressure back up allowing cold water into the system.
Re-check the temperature again using a temperature probe.
When the temperature drops below 50°C, press the reset button.
Does the appliance reset ?
Reset is confirmed when the display reverts to standby and shows '0'