You can use wugfresh's Galaxy nexus root tool kit to fix it. I came from an N1 to my current GN and have lots of experience using Rom manager and flashing roms.

Recently I rooted and unlocked my GN and flashed a rom off Rom Manager. When it finished and rebooted it went into a boot loop. I was able to use the Gnex root tool kit to reflash it to a stock Nexus firmware image and getting it working again. Yes it does un-root it when you do this BUT you can use the tool kit to easily re-unroot.

First time I have bricked a phone and was sweating bullets......happy now....thanks Wug!

P.S. Easy to do and even a noob could figure it out. I dont have the link to wugs kit, google it, its a free download as well.