This subject has come up before, If I had a safe with an electronic lock, I think wiring in a jack for an alternate power source would be a great idea, won't help with a component failure, but will work for a power failure, access the battery from inside the safe, tie into the power supply wires and put a jack in the door in a remote location with some type of cover, even a firearm or optics sticker, and in case of power failure, plug in a dc charger and away you go. I have a home made safe for sale, that is very stout, but unless you live in the DFW area of TX, would be expensive to ship.
Good luck