I flashed the kernel from here http://forum.xda-developers.com/nexus-6/development/kernel-stock-kernel-root-color-control-t3218958 and it went away.
How much space do we need in system in order to add a line to the build prop?
Sent from my Nexus 6 using Tapatalk
I have been able to edit mine and store a backup copy without any issues. Just adding a line should be no problem....
I just did the update on my phone. I had been running 6 with root and unencrypted with TWRP recovery. What I did was flash the new radio and the system img from fastboot. Rebooted to recovery and reflashed my no encrypt kernel and SU package, wipe...
Your Nexus has a screen "bug" . lol
I believe you have to press VOL+ or VOL- white trying to boot into TWRP. I think it worked for me when I had that problem. Hope it helps you
If you have root you can use goo manager to reflash twrp.