Hi and thank you for your question. My name is ***** ***** I will be happy to assist you.
Did anything happen to the device should as a drop to the floor or being hit by another object? Sometimes a master reset can resolve most of the issues.
To perform the master reset:
a. Power off the forerunner holding the power button until it turns off.
b. Press and hold UP ARROW BUTTON and DOWN ARROW BUTTON
c. Press but don’t hold the POWER BUTTON for a second or so second – device should turn ond. Wait for 1st beep then release UP ARROW BUTTONe. Wait for 2nd beep then release DOWN ARROW BUTTON
Give that a go and let me know on the restart if the buttons are now functioning as they should.