So very shortly, on my C3, I got my old battery changed at Carglass (France). I was then having troubles starting it - the car was saying I need to press the break to start it while I was already pressing / or the motor completely failing to start. At some point I stopped at a red light and the start & stop activated. When pressed the accelerator again, the car completely want black out (no light, nothing on the screens, no contact, not even able to lock the doors except for the conductor one). When I checked, the battery was disconnected. I connected it again and the car works like a charm. Carglass now says it is impossible and the battery is either well connected or it doesn’t work. What do you think ?