The relay is the heater relay you should hear circ pump cut in for a few seconds to try and build up the pressure then go off if it does this check pressure switch if it doesnt cut in at all check circ pump itself if they have been stood a while they have a tendency to stick/seize or impeller could be blocked but if it is the circ pump itself sit down because they are expensive!!!
Dunno if you’ve this one repaired yet, but i’ve come across this problem a few times with Miele d’washers, sometimes its as simple as a blocked inlet water filter & machine slow to fill .. hence not enough water in system to operate pressure switch..