Lumia 640XL screen black for no reason

Hi Guys, this is my problem: I have a Microsoft Lumia 640XL and until this morning I was using it normally, write messages, calls, etc. then I just put it on a table, looked for time and screen was full black, completely not working. Vibrates when I try to charge it and I can access memory through PC. I tried to hard reset it but can't see the "well known" exclamation mark for obvious reasons.

So, what shall I do?

I can repair it myself, fortunately I have some skills, but I'm curious if there is another way.

Thank you in advance and sorry for my bad english (Italy, land of pizza :D)