M3800 screen dead

The screen on my m3800 has stopped working.

I shutdown as normal when I left the office and when I started it up back at home an hour later it was dead.

If I connect to an external monitor all is OK so it's definitely the screen that's at fault.

A couple of times during rebooting vertical black and white lines appeared for a few seconds then it ll went black again.

Is this potentially just a loose connection or is the screen knackered?