If you have no power to the Winegard power supply (not a booster) then the booster located in the head of the antenna cannot work and you will therefore get just about no reception. The dealer who fixed it did not fix it.
You can go on the roof and remove the coax from the head of the antenna and put a voltage meter on the center wire of that coax. My guess is that you will find no voltage and 12-13VDC is required. If I am right you have a blown fuse somewhere to the Winegard wall plate, a bad wall plate (12V power supply) or a bad cable/connection. I have frequently seen dealers reverse the Cable and Antenna connection on the back of the wall plate as well which would result in no power to the antenna.