Set Appliance State:

Set Multimeter to AC Volts Set meter to measure AC Volts
Turn Hot Water Tap On
Isolate Mains Power to appliance as per TOPs P4
Gain access to PCB (use insulation mat as required)
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Is there mains voltage present on CN3 connections PL (brown) and PN (blue) on the sequence PCB?