Replace BMW Key Battery It might be time to replace your battery if your BMW key won't open your car or turn the engine. It's simple to fix. All you need to do is remove the key fob cover then carefully remove and replace the battery, then insert it gently. https://car-key-reprogramming77131.blogunteer.com/29374246/speak-yes-to-these-5-bmw-key-fobs-tips