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