Getting a new gun safe-  considering a Sentry, can get an electronic one for a very good price.   My concern is, if the electronics go, how do you get the safe open?  Is there a back up key or something?

If you put a back-up key lock on it why bother with the electronic lock?  If you put a never fail battery on it you don't need a back-up key.

What's that you say, there's never been a battery made an owner can't cause to fail?  That is a paradox.

I keep my back-up keys for the electronic bedroom safe in the big garage safe.  If they can get them out of that one, it doesn't matter anymore.

I have one and it is very simple.  The keypad is battery-operated.  To get the batteries in, you have to slide the keypad faceplate up and off the mount which reveals the battery compartment.  The keypad will still be attached with some wires.  You then can pop the battery compartment out which reveals a keyhole for one of 2 keys that come with the safe.  I keep these keys in a safe deposit box because I don't want them in the same house as the safe.  The whole lock area is very reinforced to prevent drilling.

the keypad also has a low battery warning light that lets you know when to change them, but the batteries last for a few years before you have to worry about this.