I think you forgot to flash boot.img which is in the custom rom zip file
Due to being unlocked you need to flash boot.img on every flashing new custom rom,if you were s-off ,it is automatically done as I know
And make sure you have wiped data,cache and dalvik cache before flashing new rom
here are the some links and videos to help you on flashing boot.img
While we are all wondering when Google will decide to officially release … more
19 Aug 2014
By Tomek Kondrat
XDA Developers was founded by developers, for developers. It is now a valuable resource for people who want to make the most of their mobile devices, from customizing the look and feel to adding new functionality. Are you a developer?