Hi,
MigaoMiner: I had exact same problem, because my board is just missing chip for sd card. With this method you dont need boot from sd card. Just keep jumper in default position, connect uart bridge, disable ssh as described and then you can install another firmware like braiin os.

Jacoob007: as far as I know this is not possible at the moment. We can just hope that bitmain will change their minds and in next fw we will have option to enable ssh ...

Thanks and regards,
MK

Hi,

Unfortunately there is another type of board. I tried boot from SD several times but immediately after I switch jumper 4 to boot from SD position I got both leds green + red constantly on and nothing happen. After some google investigation I found that my board is missing some chip close to slot as you can see in images :-(

I ordered CP2102 UART to USB (https://www.aliexpress.com/item/1859102520.html) and hope that I will be able enable SSH on secure firmware or boot from tftp to remove secure firmware from my board.

Image 1 - Antminer S9 control board Ctr_C41 Vers: 1.20
As you can see there is some sticker with some chinese + TF Card
https://pasteboard.co/InjoGnE.png

Image 2 - detail of missing chip ..
https://pasteboard.co/InjppJn.png

Will add more information after converter arrive.

Thanks and regards,
MK

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Hi,

I prepared guide how to enable ssh on secure firmware via serial console for those without functional SD card slot. I will also add steps how to unbrick antminer without sd card slot.

https://docs.google.com/document/d/e/2PACX-1vSu6XGV4Q40TerRPccB7xxTf2sKNkp1Bkwkdz4ILhIaa9qaT-NvZWtFrIBiwpRsG3NRlzvwQkbKyvsv/pub

Thanks and regards,
MK

currently waiting for cable but I think the steps will be:
1. setup tftp server / load uImage from not secure kernel to root
2. issue tftp $0x2000000 ${kernel_image} - kernel_image = uImage
3. bootp to start kernel
4. upgrade firmware via web interface
will test it when cable arrive not sure if it will work as kernel will be from different version of firmware

Hi,
I am just locked my self with new secure firmware :-( and when i try boot from sd card nothing happen immediatelly as i switch last jumper to boot from sd and power on both leds green and red are constantly on :-( I am thinking about using your method to downgrade  firmware to not secure one. You mentioned tftp server could you please give us more info how to replace kernel image in nand with tftp ? I think this will be very helpfull to community as bitmain is not playing fair ... May be easiest way will be just enable ssh throught serial console but i am not sure if this is possible. Many thanks for your help. MK