Replace BMW Key Battery If your BMW key isn't opening 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 gently put it back. Follow these steps https://thekeylab07325.get-blogging.com/30543012/a-guide-to-bmw-key-fobs-from-start-to-finish