stopped working? or a fault - more details needed - what are the lights doing - VM will get to the thread in about a week and will run test - apart from that you have to ring and book a tech to come out
Have you tried the obvious is turning off the power, waiting 5 or 10 minutes then turning back on?
If that does not work, you may get a quicker response by phoning in and reporting the fault. Best to call about 8:30 to 9:30, as this used to be Alexa busy time and should avoid the overseas call center?