Hi Dave,
Thanks for your quick reply and sorry for taking ages myself. I only today got around to removing the heater unit and yep, no continuity so I suppose its dead and I will be needing a new one.
For anyone reading this later – this is a super easy job. All you have to do is:
# get your dishwasher disconnected from water and power,
# take the filter and all the bits that you should clean now and then out (the mesh and the filter)
# aspirate all the water from the bottom with a turkey baster or a pasteur pipette (same thing)
# unscrew the little metal side panel on the bottom right hand side as you are looking at your dishwasher.
# take the panel off
and the do what this guy is doing
https://www.youtube.com/watch?v=BKAQmq9MPN8&t=299s
All you need is a screwdriver and a turkey baster
Thanks for your help,
Arek