Has the ringer in your HTC Tytyn 2 (AT&T 8525) stopped working? The phone is fully operational but none of the ringer sounds can be activated.
Turns out there is a design fault in the AT&T 8525 where over time the 'ringer' connecter dislocates from the phones motherboard.
5 minutes and you can fix it as good as new.
Step 1: Remove the back cover, remove the battery, remove the 4 small screws circled in red below. Congratulations you are further along than any iPhone :P
Step 2: Partially seperate the rear cover with a credit card.
Step 3: You only need to open it as the 'OK' button, as long as you can see this small white connecter with Red & Black wires then this is far enough.
Step 4: use a small set of teezers or some other object to push down on the connector (in the direction of the button towards the motherboard).
Reboot your phone and it's as good as new.