Do you have a backup of the router? If so you can do a netinstall onto the CF using a cF adapter and any windows machine running Netinstall. This should repair the problem as it initiates a fresh install when the CF is first booted on the target machine. It wont affect the license either. Afterwards you can restore from backup. I have found certain (x86) hardware does not like the upgrade.
You can also try the same directly on the target machine using a CD install. It will also retain your license using this method.