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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. :wink:


Yes. It was my fault thinking "newer is better". Now I choose to stick to 1.00 which can ...

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:
./makemkvcon f -f '/home/xiaoxi/Downloads/mk-firmware-pack-20200720/MK/sdf ...

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 ...