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I think that the tendency to illuminate even when not touched for some time, is a clue as to why the safe's combination keypad is not working - the batteries have run down again.
If the keypad illuminates when untouched, then either
A. there's a stuck button on the keypad, triggering the keypad light, which drains the batteries down, and then the keypad doesn't work at all (until batteries are replaced yet again), or
B. the safe is placed so as to have one of the buttons held down by some nearby object? or
C. the number keypad is otherwise defective in a way that drains the batteries and/or turns the light on leading to (A) above.
Solution indicated to all that, if it is true, is to replace the batteries again with new ones. Unfortunately the safe's keypad may be using up batteries too fast. I'm not sure if Sentry would fix that problem for you under warranty if the safe is 4 years old... please tell me exactly (with several months or a half year) how old the safe is, measured from its date of purchase.