Burberry Sport Mens Diving Watch BU7720 Swiss Made 200M *Not Working for Repair

Burberry Sport Men's Diving Watch Style: BU7720 Not Working - Please Read - For Repair Red Knob Turns and Works Fine, Black Knob does not turn, not sure what is wrong with it cosmetically it looks okay but is just stuck not turning. Near the 40 looks like there is a bit of rust, needs to be cleaned a little under the glass. Band is in pristine condition, no issues whatsoever. It looks and feels like it was barely used