Replace BMW Key Battery It's probably time to change your battery if your BMW key isn't able to open your car or turn on the engine. It's a simple fix. You simply need to remove the key fob, then replace the battery and gently put it back. Follow these steps https://car-key-replacements44657.blogginaway.com/30688606/the-most-successful-bmw-key-fobs-gurus-are-doing-3-things