Ok, you're getting closer. Please try the following. You can disregard all prior mentions about dhcp & tftp server. 

from the sff7000 prompt... (this is the stage 2 bootloader)
setenv octeon_stage3_bootloader u-boot-octeon_rhino_itux7x.bin_bak
bootstage3

from the cust_private_rhino_itus7x(ram) prompt... (this is stage 3 bootloader)
fatls mmc 1
this will dump the boot partition. look for the backup of your router image.
you should have something named ItusrouterImage or vmlinux.64
find the image you want to load, and enter the following commands..

fatload mmc 1 $(loadaddr) FILENAME
bootoctlinux $(loadaddr) mem=0 numcores=2

this should load the desired firmware into ram, then execute it.
You'll want a 'router' image because that sets up a LAN with DHCP server making fixing / upgrading a little easier.

Once you get into Linux, you can mount the boot partition and clean up the files.
For example, you know the backup is good, so you can do something like this... 
mount /dev/mmcblk0p1 /overlay
cd /overlay
cp backup_filename correct_filename
cd ..
umount /overlay
reboot -f

please let me know if you'd like to do a webcast, I'm happy to help.