I'm having issues with my factory head unit. I loaned my 2009 XB to a friend and when I got it back the stereo didn't work. The head unit seems to be functioning fine, but there is no sound coming from the speakers. I'd like to simply swap out the unit to test it, but have no friends with XB's. Does anyone know an easy way to troubleshoot my problem? I've checked all of the fuses, etc.