It's happened twice now, the first a couple of months ago, but basically the monthly update was available and I thought the issue was fixed.
Today, I received a call and again the phone screen was black even if I held it away from the face. I could not end the call, which was a spam call, as the screen was not lit. It would not display even after pressing the power button. All the while, the spam caller was still on the phone and I couldn't do anything. I eventually started the hard reboot process by pressing the part and volume up buttons, but the caller ended the call before the process was over. When the call ended, the display showed and the phone is working properly again. I was browsing the internet at the time when the call was received. The same thing happened the first time the issue was experienced, that time it was a friend calling.
Has anyone else experienced this? Can't remember if I were browsing the first time. Unfortunately it also seems not to be repeatable.