I'm having a problem with my trackball, last night it went kind of crazy out of nowhere and when I would press a key about 30 different letters would be typed, that stopped after a couple of battery pulls and the phone was completely fine and I went to bed, I woke up and this morning the trackball button will not work, I can still scroll around with it perfectly fine but when I press it, nothing. Does anyone know how to fix this?
If the device was exposed to moisture (even a little bit as noted above), it likely has damage to the keypad contacts which are part of the main board.
You can try taking it apart and cleaning the contacts with alcohol, but it's likely time to get a new device.