Over the years the keypad had become more and more unreliable to the point where the 0 key was very difficult to press successfully, and the 4-digit access code used a 0. A service person who was replacing the battery added an access code which was the old one but with the 0 changed to a 1.

A year or so on, and the same problem has developed with another key, so I looked into adding an access code myself. Turns out, the procedure for changing/adding access codes requires a master access code to be entered. The default access code according to the manual is 123456 or 000000, but the first one doesn't work, and the second one involves pressing the 0 key, one of which I don't have.

I believe these keypads usually work by pressing a conductive polymer against contacts on a printed circuit board. I would like to try cleaning this contact interface. Does anyone have any experience with this? In particular:

How do they come apart?!  There are no visible screws.  There are small openings on the "front door" hinge edge that look like they might have spring releases behind them.

I'm presuming it's possible that the keypad has some sort of anti-tampering protection.  Will disarming the system, powering down the control box and disconnecting the Lead-Acid battery be sufficient?   There is an outside squawker which I presume has a battery in it (though we've never replaced that one - whereas we've gone through two control box batteries in 10 years).

Any comments appreciated.