Galaxy Aqua 400si wont start?

I have the galaxy aqua 4000si and it has just stopped working.

There is power to the shower, but no lights on, there is also approx. 3.8 ohms at the solenoid.

I have two of these shower units and I have swapped the circuit boards about and that is not the problem, as the one which works still doesn't work on the broken shower unit. Help Please