Default Cannot upgrade to 4.4.2 on Nexus 7

Hi all,

I have a nexus 7 wifi tablet running rooted stock 4.4 (unlocked)
Two months ago I received a notification telling me that Android 4.4.2 is ready to be installed. I rebooted but (beacause of cwm recovery?) nothing happened. I used wugfresh toolkit to restore the stock recovery (got success message)and then tried to update again but after reboot there is a progress bar that reaches 50% and then an exclamation mark. From that point I can only force poweroff and then poweron to make the tablet boot again. Does anybody know whats the problem? Or If I can install 4.4.2 rooted somehow?

Sent from my Nexus 7 using xda app-developers app