how can i fix myaquatronic plus 2?

you would need to check the microswitches to make sure they are providing power to the solenoid valve that allows water to come through to your shower.The power should be present when you turn the knob to cold. I would disconnect the power first and check the continuity of the microswitch at the very back of the power knob(once removed), then carefully check with the power on, but only if you are confident at testing 240 volts AC whilst standing in a wet area.IF NOT DON'T DO IT.

GRINGO
October 2009