The cable that carries the video signal from the mainboard, through the hinge assembly and up to the LCD panel usually utilizes Low Voltage Differential Signalling, and hence may be described as an LVDS cable. In order to facilitate assembly or replacement, the connection at each end is via a low profile socket, sometimes press-fit, sometimes with a clamping action. If the contacts tarnish there can be artifacts on the video signal that can result in symptoms similar to what you describe.
If that's the cause, and the connections are press-fit, simply withdrawing and refitting them a couple of times can often polish up the contacts enough to restore function. Where there's a clamp action socket, it's best to use an electrical cleaning spray and cotton tip to clean the cable/loom contacts, and whilst there are commercial cleaning swatches for the sockets, you can at a pinch use light card or heavy (e.g. 120-160GSM) white paper damped with contact cleaner to insert where a flat cable goes and draw out with slight pressure on the clamp, to wipe across the contacts.
If that cable has fractures, as OldPhil commented, moving it by opening and closing the screen will provoke the fault, although that usually causes more pronounced symptoms like flashing screen or loss of image.