Shower problem

I think you have a faulty solenoid valve which unfortunately is now obsolete, however it is possible to just replace the coil on this unit.

It may be your solenoid valve, you can check it if you have a multi meter, you should have a reading of at least k3.5 ohms, across the two terminals any less and you need a new valve. (Check the valve in the failed state.) (When it has stopped working!)
If there is power getting to the solenoid and it is not operating then there is a good chance that you have a faulty solenoid.

www.youtube.com/watch?v=NzJjzWqxesc

The video is intended as a guide and does not cover every shower.
If you don’t have a multimeter  we sell them  with a guide on how to use them for checking and testing the various parts of your shower.

Apart from helping to fix your shower, they are really useful for checking you have a power supply to appliances, for checking fuses and letting you know much power you have left in batteries

(So you will know if they are good or not) and lots of other jobs, in short they are well worth a few pounds
www.showerdoc.com/installation/electrical-products/SKYTRO-600-005-Digital-Multi-Tester

www.showerdoc.com/hydra-universal-electric-shower-solenoid-coil-no-valve-included-27600