Replace BMW Key Battery It could be time to change your battery in the event that 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 then gently put it back. https://carkeyprogramming30405.bloggin-ads.com/53563813/a-how-to-guide-for-bmw-key-fobs-from-beginning-to-end