Replace BMW Key Battery It might be the time to change your battery if your BMW key won't open your car or turn on the engine. It's an easy fix. You simply need to remove the key fob, then replace the battery and gently put it back. Follow these steps https://car-key-reprogramming77131.blogunteer.com/29517447/10-bmw-key-fobs-related-projects-to-stretch-your-creativity