Replace BMW Key Battery It's probably the time to change your battery in the event that your BMW key isn't able to open your car or turn on the engine. It's a simple fix. It's as easy as removing the key fob, replace the battery and gently put it back. https://carkeyreplacements46855.blogdanica.com/30035700/say-yes-to-these-5-bmw-key-fobs-tips