I have a fix for the nasty bug which stops you booting from USB in SeaBIOS on the ASUS Chromebox. It’s an updated CBFS filesystem for the RW_LEGACY slot of the firmware, which contains an updated version of SeaBIOS. Simply download the file and apply it in the Crosh shell like so (you don’t need hardware write-protect disabled)
sudo flashrom -w -i RW_LEGACY:asus-chromebox-SeaBIOS-new.bin
Beer me on your way out!