Today this happen, any ideias?
Screen lines are generally a sign of HW failure, sorry to bring bad news. If you're lucky it's just the internal ribbon screen connector that got loose. I'd open it to see, but of course, this voids your warranty in case it's still valid, up to you if the risk is worth it.
Contact HW support to see what they say, you will prob have to send it in for repair I think.
This is how it looks inside
The two wide golden ribbons are for the screens.
And here's a direct link to our Hardware department: https://bit.ly/NISupport_Hardware
Thank you!