Replace BMW Key Battery If your BMW key isn't able to open your car or turning on the engine, it may be the time to replace your battery. It's a simple fix. You simply need to remove the key fob, then replace the battery, and then gently put it back. https://the-key-lab18569.goabroadblog.com/29529066/why-bmw-key-fobs-still-matters-in-2023