I'm not on a Mac, just a Windows pc and I'm using Wug's toolkit:
Nexus Root Toolkit v1.5.4 | WugFresh
If I were you, and I'm unsure now that I know you're on a Mac, I would flash the factory image, then root and enable the option to install CWM recovery, after that completes I would download the OTA update that I linked you in my previous post to your internal sd card, then boot into recovery and use it to flash the update.
Did you at any time install cwm or twrp recovery to your device?.. if you did, then you'll have to install the update via recovery or flash the factory recovery back to your device.
Sorry if this isn't very easy to understand.