Why does ml350 key not open the door manually?

The ML350 key may not open the door manually due to a few reasons, such as a dead key fob battery, which prevents the electronic locking mechanism from functioning. Additionally, if the vehicle's central locking system is malfunctioning or if the key itself is damaged, it might not engage the lock. Some models also have a hidden lock feature that requires a specific technique to unlock manually. It's advisable to check the key's battery and consult the vehicle's manual for troubleshooting steps.