The battery may be almost dead, so it will light the lights but not kick the solenoid. A couple of years ago I read on a gun board about a trick you can use with an external battery connected to the safe body and the other terminal to somewhere on the keypad to "boost" the internal batteries. However, I can't seem to google it up now. Not very helpful, but if someone can dig up that technique, it would be nice.
I didn't really pay that much attention at the time, since I don't use safes and frankly would not trust an electronic safe anyhow.
ETA: See ETA below.
Amusing side note: My younger son's neighbor had his car battery go dead because they left something on inside it and the electronic lock wouldn't let the car open and the key was inside the car. I told him to get under it with extension cables to an outside battery and connect neg to car chassis and hit the starter terminal with the plus while the neighbor kept punching the remote control or the door combo, I forget which. Told him to be careful of sparks. Door lock opened right up and they could open the hood and give it a regular charge or jump start, I forget which.
Neighbor gave him 20 bucks.
But I didn't see a dime of it.
For decades I have kept spare keys to everything squirreled away everywhere.
Terry, 230RN
ETA: I wonder if you could probe around on the keypad with a voltmeter to see if there's any voltage anywhere on the keypad (to the safe body). If you find it, that probably is the place to connect the external battery. Just thought of that.