I had an interesting experience with my stack on electronic combo keypad today when I touched it...I accidently zapped it after walking across the carpet. Damn static electricity.
Was kinda worried, because some numbers would "work" but some were "dead" when I pressed them. Uh oh.
Took the battery out, and gave it a rest for a couple of minutes.
It's fine now. Gotta try to locate the manual to see if anything is mentioned there about this.