After a few false starts, I got my device rooted. (Yay me!)
Now, I'm stuck in the "flash rom" step.
First, I downloaded nakasi-jzo54k-factory-973f190e.tgz from google, then I unzipped it.
I then used the Root Toolkit, Advanced utilities, Boot/Flash image, Boot (temporary) tool and pointed it to the file bootloader-grouper-3.41.img.
My nexus rebooted into fastboot mode, and it says "booting downloaded image".
It's said that for almost half an hour now, and I'm getting nervous.
Should I wait longer? Would I be risking breaking something if I just unplugged it and rebooted the nexus?