Replace BMW Key Battery It could be the time to change your battery in the event that your BMW key won't open your car or turn off the engine. It's a simple fix. You simply need to remove the key fob, then replace the battery and gently place it back. https://the-key-lab42575.link4blogs.com/52047969/the-most-successful-bmw-key-fobs-gurus-are-doing-3-things