the multi information display will tell you when the battery is low in the keyfob. You have plenty of time to change it. Then if it does die, you can still start the car. The RX does not have the plastic cover over the door handle which hides the keyhole so there is no need to pry off any cover. Just insert the metal key into the door handle and open the door. Then hold the key fob close to the start button and it should sdtill work