How do I fix it?

See this:

https://www.showerdoc.com/mira-sport-10-8kw-post-1998-shower-spares/question/power-light-flashing---shower-won-t-turn-on-81492#:~:text=Power%20light%20flashing%20%2D%20shower%20won't%20turn%20on,-We%20have%20a&text=It%20may%20be%20your%20solenoid,valve%20in%20the%20failed%20state.)

But note the resistance is expressed strangely. The figure is 3.5k Ohms.

Fhui
October 2022