While you wait for answers, we may have found some information which could help you.
Success
Message
Boiler over pressure on the hot-water side?
Aquadart shower seal?
Fasco?
How can I mend my Neptune Exotic shower?
Replace cord in shower screen?
Grohe push button flush?
Almish heater surge model w15?
Mira advance atl electric shower?
Mira excel thermostatic shower mixer?
What parts do i need to get water flowing again?
How do I fix it?
Thermal cut out switch?