How to Downgrade Xiaomi Dafang (serial console is available)

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• exact camera hardware: DF3-00541409
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Description

I need to downgrade the firmware of my Dafang camera. The prescribed method (put demo.bin on sdcard hold reset button and power on while holding it for 10 seconds) does not work. it just continues to boot and it starts speaking chinese (most likely that a QR needs to be shown to connect)

What did you do to debug the issue

I connected the FTDI serial convertor and looked at the log, just doesn't seem to be reacting to the holding of the reset button at all.
I thought about flashing from the serial console. But all guides are based on U-boot which isn't on a stock camera.