Stuck at Redboot while recovering X3 Modem

do you have the rest of the console output?

did you get to enter in the 'passwd' command?

also if you enter 'ifconfig' you should be displayed what the IP address of the modem is. If not you can set it.

At the /# Linux prompt, enter the following command to view the interface configurations:
ifconfig
The interface configurations are displayed.
2 Annotate what is displayed as the first interface (ixp0 or ixp1); this information is needed in the
following steps to configure the IP address and cabling.
What follows after the inet addr and Mask fields under the first listed interface is the
iNFINITI unit’s IP address and subnet mask.
3 If a valid/correct IP address and subnet mask were displayed in Step 1, skip to Step 4. If a valid IP
address and subnet mask is not present, configure it by entering the command:
ifconfig <interface> <ip address> netmask 255.255.255.0
where:
interface = ixp0 or ixp1 (as noted in Step 2)
ip address = desired address (192.168.0.1, for example)
Note: Changing the IP address using this method is temporary; it will be overwritten by
the IP address configured in the Options file when the file is read, which occurs
during reboot at the end of this document.
4 Enter the following command again, to confirm the interface configurations:
ifconfig
Note: Anotate what is now displayed as the IP address (inet addr) of the first
interface; this information is needed in later procedure steps.
5 Turn on the SSH daemon by entering the following console command:
service sshd start

I believe there is also a command to view the routes in the modem, you might have to alter (default gateway) this so you gain access to it.

good luck!