OK, have a few more minutes now to talk over the issues.
During the evolution of the linux kernel, at some stage (not clear when) the name of the nand driver was changed. It changed from nand_mtd to orion_nand. Now this name is needed to be passed to the kernel on boot, and alas the install script for zylnx (
http://de7.mirror.archlinuxarm.org/os/nsa3x0/) never got updated. Now this line is passed to the kernel in uboot, and this doesn't get updated (or rather the enviroment variables don't get updated after install). So the wrong line gets passed by uboot to the kernel.
So first thing is to correct the parameter passed to the kernel in uboot. This you do be rewriting the uboot enviroement variables, usually from inside linux. This gives the next problem, often the adress in flash where the enviroement variables are held is set wrong in /etc/fw_env.config. So you need to correct those first. You can check this works with $this->bbcode_second_pass_code('', 'sudo fw_printenv'). Once this is corrected, you can update the bootargs_linux variable to the correct value for modern kernels.
Doing this means that after a reboot you get read/write access to the flash, before with the wrong name, you just get read access.
Next issue is that uboot likes the mac address of the ethernet set correctly - and you are going to loose this when you rewrite uboot. So you need to take a copy of this.
Then you can rewrite the flash with the new uboot and its enviroement varaibles.
Now new uboot, has a different memory map than the stock uboot. So you need to update /etc/fw_env.config to the new value. After doing this you can rewrite the mac address to the uboot env variables, to the value you saved before.
Next its best if you clean up any /boot mounts you have. Stock uboot only could access ext2, so where users wanted root to be ext4, boot needed to be a seperate partition. Now the new updated uboot can read ext4 - so it makes sense to undo any changes you have made to /boot - and have that directory as part of the main filesystem.
Finally you need to make sure that the uboot knows where to find the root filesystem, am not sure the logic in the script I posted yesterday is infalible - so I'd check this carefully.
After all this, you can reboot to the new uboot and dt based kernel.
Wish it wasn't this complex. But my conclusion is you can't escape from most of this. I can't see how switching to stock install would work, as e.g. there are still old values on
http://de7.mirror.archlinuxarm.org/os/nsa3x0/ - and you can never update with those. Ideally this would be cleaned up at some stage, but there doesn't seem much entusiasm behind this.
Hope this helps.