If your combination does not work, call Sentry customer service. Before you do this, make sure you batteries are good. If the batteries are good, bypass the battery pack and use a regular 9-volt. If that fails hit the safe with a rubber mallet to try to get the actuator to engage. You can find more information here:
. http://callitout.com/quotes/index.php/forget-about-it/55/sentry-fire-safe-wont-open-its-broken/