Thermostatic electric shower low pressure display always on

[TryAgain1]

Identify the low pressure microswitch, it may be the one in your photo above, remove (with shower isolated) the wires from both terminals and you should get continuity across the terminals with the M.Meter set to resistance, Ohms, because the switch is or should be NC (normally closed), the one shown is a NO one.

You might be able to push the "switch" (shown above Honeywell on this one) in/out with something to see if the M.meter reading changes.

View attachment 422927

Is this micro switch ( https://www.showerspares.com/search/triton-microswitch-22012460/) electrically (electrical contacts) or mechanically (black push button top left?) controlled? Is the microswitch being put in the 'always on' position by the 2 brown wires being twisted?

 

[Johntheo5]

Is this micro switch ( https://www.showerspares.com/search/triton-microswitch-22012460/) electrically (electrical contacts) or mechanically (black push button top left?) controlled? Is the microswitch being put in the 'always on' position by the 2 brown wires being twisted?

Its mechanically operated by its push button which in turn is pushed by the (a) diaphragm when the shower is switched on and the pressure builds up, the same diaphragm will push the two (or only one, if Eco is selected) ) power microswitches up/on at the same time. The two wires being twisted together shouldn't cause the neon to illuminate. If that switch has only two terminals, you could remove one wire (after shower isolation) and then switch it back on and see does the neon stay off.
If, and it may be quite easy, after removing the terminal wires (shower isolated), remove that microswitch and press the button in/out and check the contacts with a multimeter. Also look for any details on the switch like shown on the one shown in my post #15.