Probably a failed solenoid valve coil. Look at this site. There are a bunch of questions towards the bottom of the page which may give you what you want. Alternatively post your own question there.
https://www.showerdoc.com/gainsborough-energy-2000x-shower-spares
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https://www.showerdoc.com/gainsborough-energy-2000x-shower-spares/question/gainsborough-energy-2000x-no-water-when-i-turn-on-56745
Anon
February 2017