RAM 2500 2019 Owner's Manual page 24

22 GETTING TO KNOW YOUR VEHICLE
2. Slightly remove the emergency key from the key fob,
approximately 10 mm. The blade of the emergency key
should just become visible.
Emergency Key
3. Holding the key fob with the button side facing down,
use the emergency key to pry up the battery cover until
the cover releases from the key fob housing.
Key Fob Back Cover Removal