Hmm, I can almost guarantee you it's a bad box, you can hook up component (the red blue green) see if it makes a difference, but like I said, most likely a bad receiver. Was the first tech a subcontractor? There was a red flag when he tried to bs you, you should have kicked him out on the spot.
Not all of us sub contractors are that way, you make us all look bad. Dish installers BS too.