My iPhone X had a fault this evening (second time I've had an iPhone X die on me) the screen went bright white all of a sudden and then turned black, and it won't come back on.

The touchscreen itself appears to still be working as I can click roughly where the lock buttons would be and feel haptic touch but it's the display itself that is completely black. I haven't backed up in a while and need to back it up before I send it in for repairs but I can't access it from iTunes while it is locked.

How can I unlock the screen without being able to see it? Any suggestions would be greatly appreciated.

My iPhone X had a fault this evening (second time I've had an iPhone X die on me). The screen went bright white all of a sudden and then turned black, and it won't come back on.

The touchscreen itself appears to still be working, as I can click roughly where the lock buttons would be and can feel haptic feedback, but it's the display itself that is completely black. 

I haven't backed up the iPhone in a while and need to back it up before I send it in for repairs, but I can't access it from iTunes while it is locked.

How can I unlock the screen without being able to see it? Any suggestions would be greatly appreciated.