Antminer L3+ control board stopped working

[immolated]

When I power my miner on, I can't open the web interface, nothing shows up on IP scan, ethernet lights up but no other lights (red/green) flash. Fans stay on super low and never spin up. Does not respond to holding reset or IP button factory reset methods (tried all 3 reset methods). Tried different PSU.  Tried loading new firmware on an SD card, but when I insert the SD card and power up the board, I do not get the simultaneous red/green lights coming on as you are supposed to when it signals its loading new SD firmware. Nothing happens except flashing ethernet lights and the solid red 5v/3v power LEDs.

I've narrowed it down to the BB board itself (the smaller removable board with ethernet port), because if I pull it off the pins and swap in a different miner's "BB Black v 1.8" board, it works just fine. I did some probing with a voltmeter and every point that a working board has voltage, the non-working board also shows voltage. The TI A8 Processor has power just fine.

Any other options or troubleshooting I can do?

[1715665073]

1715665073

[onegiantcock]

FWIW a used L3+ control IO w/BB on eBay for $25.   

[immolated]

Got one, but I'm a fixer, more interested in what went wrong and how to fix it. I found an S9 guide that used Putty and a serial connector to force a new flash of the ROM, but I can't find anything for L3+ boards (no explicit TX/RX pins). Anyone know how.

[saschamo]

Hi,

did you found a solution?
I got the same problem

Thanks

Sascha