Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4
Set Multimeter to Resistance Set meter to measure resistance
Remove connector X14 (red wires) from PCB
Check temperature of heatbank (it should not be in an overheat state i.e. below 93 degrees C)

Measurement:

Measure resistance across the two red leads at the disconnected connector.
Reconnect connector after test.