Nearly bricked my cooler
but upgrade thru USB cable is definitely possible using the eSlick cmdfile tool.
I did extract the u-boot from the archive and sent it to the Cooler using cmdfile -u and the nand was updated. I guess i simply choose the wrong one because the Cooler started to behave odly ... So if you want to play with it better to start with the fs rather than the u-boot
Back to normal after a re-install of the firmware. Kudo to the SD upgrade for being so robust.
P.S. Do not try if you are not sure