Electronics Repair Questions? Ask an Electronics Technician
If you have entered the correct combination but the safe won't open, then the mechanism may be jammed - try hitting the door with a rubber mallet to help loosen it up.
Unfortunately it is not that easy - these safes are designed to be very secure.
I would recommend getting in touch directly with Sentry to firstly check that you are using the correct combination:
If the combination has been unlocked but the door is stuck closed then you can try getting the crowbar in close to where the four bolts are - see the following image: