weakness or defect?

Easy to use wifi, great radio tracking, good sound with unique speaker - but here, the wheel on the side, which rotates forward or backward, and where one must press the center to confirm your choice (usual system for this type of radio), no longer reacts after a week when the press center: fragility, failure or defect? Back to the seller and awaiting his answer, I do not know if it's fixable, warranty, and if so, whether I would resume the same model Damage