Ota AT&T lollipop upgrade leads to black screen on unlock attempts

Hi. I am having issue where phone will not come out of lock screen. Buttons light but screen stays black. I can reboot and use phone so I know it is not hardware. I can still blindly touch screen and maybe get past lock but stays black til I reboot.

I have tried cache clearing and full reset to no avail. Only option I see is full root and alternate rom.

Please help