This seems like the same problem I am having. If I allow the display to go to sleep, I cannot get it to come back on. I can change to terminal with Ctrl+Alt+F1 and restart lightdm or just reboot. In the meantime, until this bug is resolved, I have disabled turning the display off to save power.
The display does still go to sleep at the login screen, however, it will come back on from there. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1507346 Title: Back light off after sleep mode To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1507346/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs