The Sentry A3807 safe features an electronic lock with six bolts. It's fireproof and can withstand heat for up to two hours, protecting CDs, DVDs and USB drives up to 1,850 degrees Fahrenheit. If a yellow light is flashing on the outside of the safe, it means the safe's batteries are low and need to be replaced. If the electronic lock is working but you still can't open the safe, you will have to open the safe using the combination dial.
Turn the combination dial until the safe's pointer is at zero. Insert the safe's key inside the key lock on the outside of the safe and turn it clockwise until the plunger on the outside of the safe pops out. Remove the key.
Turn the combination dial to the left, passing zero three times. On the fourth rotation, stop at the first number of your factory-set combination. The pointer should be pointing at this number. The combination is printed on the front of the owner's manual that came with the safe.
Turn the dial to the right and stop at the second number. The safe's pointer should be pointing at this number.
Turn the dial to the left and stop at the third number of the combination. If there are four numbers in the combination, turn the dial to the right and stop at the fourth number.
Pull on the safe's lever until the door opens. If you entered the wrong code, the safe will not open and you will have to repeat the steps with the correct combination.
Changing the Batteries
Unscrew and remove the screw from the base of the electronic lock on the outside of the safe.
Turn the electronic lock to the right until it pops off. The owner's manual says it must be turned from a 12 o'clock position to a 2 o'clock position before it can be removed.
Insert four AA batteries into the back of the lock.
Replace the cover of the electronic lock.