Weird screen issue

I've had an issue three times since I bought my flex 2 in June, the whole screen goes black for about 5 mins apart from a thin part at the top of the screen, about the size of the notification bar, which goes pink and pixelated. The phone stays on and vibrates when people call and stuff like that however I can't see for the time and I don't think the screen works. Anyone else having this issue?

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