Search button is your guide. And reffer to OpenWRT doxumentation there are plenty already. If you struggle then yes new topic.
Just out of curiosity? Is update passing now? I would advice to install package turris-nor-update and run nor-update command to make sure you are on new U-Boot.
If it does not work then read this:
But adapt that to MOX’es /proc/mtd as it might not be the same as Omnia