the u-boot from this thread works https://forum.doozan.com/read.php?3,16017 followed as described and flashed the nand. as a startingpint i used my own old gentoo image but it schould also work with the arch-linux image. used an serial connection to change the the env var dtb_file to /boot/dts/ox820-stg212.dtb and bevor i flashed the new nand i noted the old mac address so that ic an aby geos_one - uBoot