No idea, but your graphics output is Ok, so it's either the display or the cable.
If it's the display, then you've got a potentially very expensive fix on your hands - when my laptop display blew, they didn't realise I was still covered on extended warrenty, and wanted to charge me almost £650 to fix it.
If it's a loose cable then the fix costs you nothing. If you cable wiring is fatigued, then I have no idea what the cost would be, but you'll need to replace it.
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