Seems you already tried almost all available firmware for s9 miner. If all doesn't fix the issue then there might be issue on power supply you need some extra PSU to test or if not then hashboard has some shorted components that leads into this issue.
Can you tell us how much amp that fuse can handle? If it just 5amp fuse then it would blew.
I also want to suggest to check the hashboard you can follow this guide below it needs multitester to check components and test points.
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https://www.zeusbtc.com/manuals/Antminer-S9-Hash-Board-Repair-Guide.aspThat's way to much work for me...
I just wish there was a way to downgrade from Brains to the old Bitmain FW, can't do it no matter how i try as some 2 cards work on the older 2017/2018/2019 FW?
There must be a way, i stupidly presumed that when i upgraded to brains that my SSH locked boards that i had to flash to NAND with SD card removed the lock, hence allowing you to downgrade if needed.
I can't find/see a way to remove Brains?