I’m having the same problem (as stated in this other post). I didn’t quite understand which command gave the output with the errors that were found. EDIT: Okay I got it it’s journalctl -b0 -p4 --no-pager . But when do you run it? After force-rebooting whenever you’re confronted to this black screen? In my case I can’t acces to tty, it’s just force-reboot or wait till the battery is over 
And, more importantly, is the sleep problem still there for you, after those fixes?