The hardest part about changing the battery in a digital safe is finding where it is. But don't worry, it's not inside. The battery compartment is under the keypad, and has a little tiny hole for removal. If you don't have a jeweler's screwdriver that is small enough, you can use a straightened-out paper clip. The battery is a 9 volt.
Insert the jeweler's screwdriver or paper clip into the small hole in the plastic panel, just below the keypad and to the right of the keyhole.
Slide the panel to the right.
Carefully pull the old battery out.
Carefully unsnap the wire connector from of the old battery. The connections are like clothing snaps and just pull off.
Snap the connector onto the new battery. Be sure to observe polarity--it will fit only one way.
Carefully put the new battery into the battery compartment, storing the wires out of the way of the cover.
Insert the cover in its slots, and slide it back into place with the jeweler's screwdriver or the paper clip.