If you have never set the IP address of the controller before, it is automatically set with a team number of 0. So the IP address should default to 10.0.0.2.
Because of this you need to make sure your computer has a static IP address of 10.0.0.6 and a subnet mask of 255.0.0.0. If you don't have your computers IP set correctly it won't be able to re-Image the cRIO.
If you follow the directions on page 5 of the Control System Configuration manual (
http://www.usfirst.org/uploadedFiles...ation-0-5c.pdf) for updating cRIO firmware, it should work.