Hi, I would love a bit more detail. "Grey screen circle with line through it." Is this what you see on the screen? Does it take up the whole screen, or only part? Can you make/scan/upload a quick sketch? This description is extremely general, making it quite difficult to troubleshoot.
Circle or ellipse? Takes up whole screen? What color is the remainder of the screen? At what angle is the line? Is this a Lissajous pattern indicating problems communicating with the monitor, or something else? Please provide as much descriptive detail as you can, also EXACTLY how you got to this state of affairs, starting with plugging in the box and powering it on. Thanks so much.