Replace BMW Key Battery It might be the time to change your battery in the event that your BMW key won't open your car or turn the engine. Fortunately, it's a simple fix. It's as easy as removing the key fob, replace the battery, and then gently put it back. https://carkeyreplacements76584.pointblog.net/why-everyone-is-talking-about-bmw-key-fobs-today-71878616