On my 275 Contemporary, when the door is closed and the Lock symbol is pressed to lock the door, the lock beeps 3 times. When the door is open and the Lock symbol is pressed to lock the door, the lock doesn't beep.
Make sure the User Code is correct and that the Lock symbol is pushed after entering the User Code. If the door still won’t unlock, use a key to unlock the door. Call technical support for further troubleshooting.