C3 Intermittent Electrical Issue

That sounds similar to an issue I had with my 2012 BMW 3 Series. The symptoms were almost identical. Have you checked the ignition switch and the wiring harness for any signs of corrosion or damage? In my case, a faulty circuit breaker was the culprit.

Thank you for your input. Could you elaborate on how you diagnosed the faulty circuit breaker? What specific tests did you perform?

Certainly. I used a multimeter to test the continuity of the circuit breaker. It showed inconsistent readings, indicating an internal fault. Given your symptoms and the potential for a heavily discharged battery, I would recommend a thorough electrical system diagnosis at a reputable workshop.

Understood. I appreciate the advice. The workshop confirmed a defective battery and replaced it. The total repair cost was 290€. The vehicle now starts without issue.