UMI SUPER BLACK SCREEN

umi.super.user

Hello
After last update my UMI Super doesn't work !
My display remains totally black but the phone still work infact the notifications led change colors and it recive calls
but when i try to answer and to unlock the phone, the screen remains black .
I reported the bug error to Umi service but without answer
Also I can't get recovery mode.
Please help me.
thank you