Shower not working - any ideas?

[AMacA]

Went for a shower yesterday morning and... nothing!

Its a Triton T80XR, when you pull the cord on the isolator switch the red neon glows, however when you press the "on" button on the shower the neon goes back out again. There is no light coming on the shower to show incoming mains (usually and orange LED comes on when the isolator is switched), however when tested with a DMM there is 230V coming out of the isolator, into the shower and through the on/off switch on the shower.

For reference it was working fine on Friday morning.

[XG332]

i had the same problem with the same shower.
We changed it.

Although i read about clogged filters restricting flow and tripping the breaker.