thanks for your reply, I will try to connect device directly to pc and Ill inform you about result
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If you boot using the sd card, you can also permanently install Braiins OS to the nand controller flash storage, this would also get rid of the evil 2019 firmware.
and yes I did it using sd card and permanently install bOS to NAND (both from web interface and ssh) and both of them completely successful in logs message! but when I changed the jumper to nand the device can not give IP address. totally it seems couldnt boot from nand.