Electronics Repair Questions? Ask an Electronics Technician
If you are using the correct code, then the lock mechanism may just be stuck.
If you hear the lock trying to open, try tapping the door with a rubber mallet to help loosen up the mechanism if it is stuck.
If the code has been reset after the batteries were depleted, then you will need to enter the original factory code that was supplied with the safe - this should be recorded in the user manual.