Replace BMW Key Battery It's probably time to change your battery in the event that your BMW key isn't able to open your car or turn the engine. Fortunately, it's a simple fix. Simply remove the key fob, then replace the battery and gently place it back. Follow these steps https://carkeyreprogramming77025.blogkoo.com/a-step-by-step-guide-to-bmw-key-fobs-from-beginning-to-end-49745545