Yea I NEVER recommend going from ICS to GB while keeping data. Some people have done it against my recommendation. I just wanted to offer that as an option. I mean if you nandroided before doing all this you can just simply FXZ back to 905, root, and restore the nandroid.
Otherwise, reboot into recovery like option 4 shows, and do the Factory Reset option. You won't have to flash anything at that point. Just go in there, use that option, and reboot. Your phone will be back to a factory minty fresh state and HOPEFULLY ADB works at that point so you can root. Then you just have to reinstall your apps and set up the phone again. Giant pain, but, that would give you a clean start.
Otherwise, reboot into recovery like option 4 shows, and do the Factory Reset option. You won't have to flash anything at that point. Just go in there, use that option, and reboot. Your phone will be back to a factory minty fresh state and HOPEFULLY ADB works at that point so you can root. Then you just have to reinstall your apps and set up the phone again. Giant pain, but, that would give you a clean start.