A firmware upgrade does not always end up as expected. Especially when you don’t have enough patience to wait for it to finish.
At last, our R&D department had a couple of days to spare, so they managed to cook proper UBOOT and openWRT images for this Kirkwood 88F6-LG02 device. It wasn’t easy or straightforward but guys down there always love the challenge!
We found many useful information here but we decided openWRT was a better choice, as no extra USB stick was needed and this device had enough flash to run it.