AlSalam, Has the Phone had the screen replaced at some point, and if so where was the replacement screen purchased? This looks like a very bad replacement screen, and not a good quality aftermarket one.
As for why the phone shut down, there should be a panic log for what happened. Navigate to: Settings -> Privacy -> Analytics & Improvements -> Analytics Data
If you copy the full panic log, and upload to fex [link|https://srcb.in/|SourceBin (my personal choice)] then post the link you get when you click Save. Update your question with that link, so we can inspect it. Note: A bad aftermarket screen can cause a kernel panic!