Replace BMW Key Battery It's probably time to change your battery if your BMW key won't allow you to open your car or turn the engine. It's a simple fix. You simply need to remove the key fob, then replace the battery and gently place it back. Follow these steps https://thekeylabcouk39537.onesmablog.com/five-tools-everybody-in-the-bmw-3-series-key-fob-industry-should-be-utilizing-70535669