The filters are clean, I removed them, cleaned them and replaced them so that's okay.
I'll suppose I'll contact an electrician on Monday just to be on the safe side, feels very risky going near it myself.
I called my plumber yesterday as the flow in my shower was weak, he suggested cleaning the filters.
The electrical supply to my shower is isolated so I am able to turn off power to the shower exclusively. My house is built in a such way though that it is impossible to turn off the water supply...