Hello guys. I just bought a demo fender american pro strat from sweetwater, the thing is, the guitar buzzes like crazy on almost all the frets from 1st to 18, almost every string (except the first one). I already checked the truss rod, the neck relief is ok, using the capo at 1st and pressing the 17th fret the space at fret 8 is 0.10. The action is fine, 4/64 at fret 12 on every string. I just changed the strings to a new set, so the strings were not the problem. The nut is fine, doesn't buzz at open strings or something. The micro-tilt is loosed. And i didn't spot any high fret. Do u guys have any idea what it can be? Can this be the reason why this guitar was as a demo? I heard that the demo guitars from sweetwater possibly were in the hands of another customer, maybe it's a returned guitar due to this same issue? Im worried because im not from usa, so i can't return the guitar. I would appreciate your answers, thank you !