Liberty Centurion Safe with digital lock. The lock would beep with each button press and you can even hear it click accepting the combination and opening the lock, but when the handle was turned the door would not open. Replacement of the battery and testing with volt meter found that the 9 volt battery only had about 7v of power. When a new battery was installed the lock opened just fine.
The manual does not have this solution. It suggests that if the combination is accepted and the handle does not turn that you have have something wedged inside or that the bars may be frozen in place. It suggests oiling the hinges, and jiggling the handle while pushing on the door inward. None of these will work though if your battery is under powered.
So before you start panicking that your safe is useless and are stuck on the phone waiting for Liberty to call you back (which they did, good customer service). However, they didn't call back until after I had discovered this solution.