Home Improvement Questions? Ask a Handyman for Answers
If the keypad still won't light up and there is no response from the keypad at all, check for any corrosion on the battery contact terminals - if the batteries have not been changed in a long time, they can leak and corrode the terminals, preventing the fresh batteries from making a good connection.
If that doesn't work, test the batteries or fit another set of fresh batteries.
Let me know how you get on...