Boot.script for ARM

I am trying to upgrade my Cubox (not Cubox-i) from 12.3. I have made a new SD-card with the 13.2 appliance image, but when I try to boot I get:

unknown command ‘bootz’ - try ‘help’

I can’t seem to find anything to help me. Do I need to create a new boot.scr, or do I need to flash my cubox uboot (the instructions for that are no longer on the web as far as I can see). If a new boot script will do the trick, what do I use?