It requires I9250 Odin, which is also attached to this post.
Firmware download: (tar.md5 file, Unpack with 7-zip)
Source: modaco forum. Downloaded from Filesonic, joined, repackaged and uploaded to multiupload.
If the multiupload link doesn't work, you can always try downloading the original rar-files from the modaco forums and filesonic:
Original modaco thread.
My own neX-files mirror:
If that doesn't work, I have a mirror on box.com here:
Part 1: http://www.box.com/s/g6p1h13nmo8j8l1jthcj
Part 2: http://www.box.com/s/eqyy9fqevc81omo70xe8
You only need this if the original multiupload link does not work.
Attached to this post, but also downloadable from box.com
Baseband is XXKK1.
To flash this follow the following guide:
1. Download file.
2. Unpack 7zip file. You should now have a 4-500MBish file with an extension of "tar.md5". Do NOT rename it or attempt to open.
3. Put your phone in Odin/Download-mode. To do this you have to power it off, then hold volume down and while keeping that pressed, press power. Your phone should boot into Odin/Download-mode. This should be reported on screen.
4. Connect your phone to your PC via USB.
5. Ensure your PC recognizes the phone as a valid "Gadget serial" device. If device manager is reporting new "Unknown devices" chances are Odin will not be able to connect to your Galaxy Nexus. If this happens, check chainfire's thread for more help on getting Odin and drivers working:
6. Disconnect your phone from the PC.
7. Start Odin as Administrator (not sure this is needed, but oh well)
8. Reconnect your phone to the PC. Observe that Odin recognizes the phone.
9. Choose the unpacked firmware file in the PDA section.
10. Choose the supplied PIT-file and make sure repartition is checked.
11. Click start.
12. Wait. Watch your phone reboot into stock.
Added clarifications about which files are needed.