Replace BMW Key Battery It's probably the time to change your battery in the event that your BMW key won't open your car or turn on the engine. It's simple to fix. It's as easy as removing the key fob, then replace the battery, and then gently put it back. https://the-key-lab80178.p2blogs.com/29385505/10-bmw-key-fobs-related-projects-to-stretch-your-creativity