Q box whistling noise even when powered off

[Patandthecats]

New Q box fitted Monday, during the night Tuesday the connection from dish to box seems to have been lost. When I came downstairs this morning, Weds, I could hear a high pitched whistling noise. Checked online and it advised to completely power off and leave for a while before rebooting. I could still hear the noise when box and TV had no power going through. Any ideas? I can't get an engineer until next week and I think I will have lost my marbles by then