If a specific key (e.g., the number 5) isn't working, check for continuity between its pad and the pads of nearby keys. If they share a "way" but the connection is open, you have a broken track.
Moisture can cause corrosion on the copper pads, breaking the electrical connection. nokia 105 rm 908 keypad ways
Before performing hardware repairs, try these simpler solutions: If a specific key (e