Replace BMW Key Battery It might be time to change your battery if 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, replace the battery, and then gently put it back. Follow these steps https://carkeyreplacements44437.blogdosaga.com/30135209/15-shocking-facts-about-bmw-key-fobs-you-ve-never-known