BP71N crossflashed to BU40N and cannot be downgraded

[ij478]

I recently bought a UGREEN UHD drive that is a BP71N which looks like a BU40N rebranded. It comes with 1.03 unpatched. So I flashed the HL-DT-ST-BD-RE_BU40N-1.04-NM00500-212005061142.bin firmware as provided by mike.
But after that I'm unable to downgrade to any other firmware such as BU40N-1.03 or even DE_LG BU40N_1.00.bin in Downgrade firmware pack. After flashing the firmware just sticks at 1.04. I have tried either adding "enc" and "de" after "rawflash" but none of them works. What should I do?

the first flash:

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./makemkvcon f -f '/home/xiaoxi/Downloads/mk-firmware-pack-20200720/MK/sdf.bin' -d /dev/sr0 rawflash enc main -i '/home/xiaoxi/Downloads/mk-firmware-pack-20200720/MK/HL-DT-ST/BU40N-N-Main/HL-DT-ST-BD-RE_BU40N-1.04-NM00500-212005061142.bin'

one of the failed flashes:

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./makemkvcon f -d /dev/sr0 rawflash enc -i '/home/xiaoxi/Downloads/mk-firmware-pack-20200720/MK/old/HL-DT-ST-BD-RE_BU40N-1.03-NM00000-211810241934.bin'

[ij478]

ALRIGHT! I fixed it!
By using the SDFTool flasher and checking how it flashes, I successfully flashed this drive.
In a word, after crossflashing, you need to manually specify the boot code.
Here is the complete flash code:

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./makemkvcon f -f '/home/xiaoxi/Downloads/mk-firmware-pack-20200720/MK/sdf.bin' -d /dev/sr0 rawflash boot="MT1959 Boot BU5 " -i '/home/xiaoxi/Downloads/Downgrade Enabled Firmware V.2/DE_LG BU40N_1.00.bin'

[Sayaka]

Instead of flashing BU40N 1.04-MK, you should have flashed BU40N 1.03-MK right away (and then possibly BU40N 1.00 without "enc"). Congratulations on figuring out how to fix the issue you were having.

[ij478]

Instead of flashing BU40N 1.04-MK, you should have flashed BU40N 1.03-MK right away (and then possibly BU40N 1.00 without "enc"). Congratulations on figuring out how to fix the issue you were having.

Yes. It was my fault thinking "newer is better". Now I choose to stick to 1.00 which can use both qpxtool and LibreDrive.