Hi- The alarm can be disarmed but locking/unlocking either front doors or the liftgate.The system may have a fault that will not allow disarming. That's rare.
The batteries may be weak or bad in the remote. To test transmitter you can hold it near the antenna on an AM radio tuned off station . Press the button and you should be able to hear the tones. I hope this helps. Please press accept if it has.Please ask if you need more info. Thanks Scott