If your BMW won’t start and there’s no clicking noise coming from your engine, the most likely culprit is a partially or fully discharged battery.
Even if your battery is fully charged, however, this type of starting problem typically indicates an issue with your vehicle’s electrical system. This might mean that you have corroded battery terminals, a malfunctioning or failing starter, or a bad alternator preventing your BMW from sending enough power to your engine to start.
Another potential cause in older BMW models is a problem with the anti-theft system. If your vehicle is unable to recognize your key, the engine won’t start. In these cases, you’ll need to get the problem assessed by a professional.