The only things it could be are the fans (which you have ruled out), trackpad (the force touch might be working on it's own, but I doubt it) or the speakers (most likely, especially since it does it at boot when it should chime).
You can try removing the bottom lid, and listening to where the clicking sounds are coming from (speakers are to the left and right of battery). If it is coming from the speakers, use a T5 screwdriver to remove them, it is possible there is dust under, or they are bad.
The best thing to do though is return it to where you got it from. If it is 2 days old, there will be a warranty :)