Replace BMW Key Battery It might be time to change your battery if your BMW key won't open your car or turn on the engine. Fortunately, it's a simple fix. You simply need to remove the key fob, replace the battery, and then gently put it back. Follow these steps https://carkeyreplacements30092.buyoutblog.com/30265317/what-freud-can-teach-us-about-bmw-3-series-key-fob