There's a common issue where the spring on the mirror breaks and falls, which renders the HUD unviewable. It's an easy fix but this sounds different. So you get the framing lines on the edges when you press the button to move it but nothing else displays? That would be really peculiar as I would presume any failure would be a signal failure and that would result in the display begin completely dead and not moving. Can you elaborate on the problem?
Try turning the engine, going outside and looking down through the windshield. See if you can see the image on the mirror and see if the mirror hasn't fallen.
