I used this method on a used L3+ I just got off eBay.  Great instructions, thanks for laying it out.

Did you ever get this figured out?
The 2019 firmware disables SSH, which means you are locked to using only BITMAIN firmware.

BUT

I just finished downgrading from the 2019 firmware.

I had to do a "Control Board Program Recovery"

The way listed on the BITMAIN site gave me problems though; I was not able to login using the default username/password

If you run into the same problem with logging in you have to modify the Control board recovery.

 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

1. Download the old firmware from here ( https://github.com/jeffpcyo/asic-firmware/tree/master/Bitmain/Antminer/L3%2B) (This is just the first place i found the 2017 firmware)


2. Download the "L3+、D3、A3-SD Tools.zip" from here ( https://service.bitmain.com/support/download?product=Flashing%20SD%20card%20with%20image ) (BITMAIN's support site)


3. Extract "Antminer-L3+-201708251737-384M.tar.gz" to somewhere (so you can get at the Antminer-L3+-201708251737-384M.tar inside)


4. Extract "Antminer-L3+-201708251737-384M.tar" to somewhere


5. Extract "L3+、D3、A3-SD Tools.zip" to somewhere ( I use 7zip, just right-clicked and extracted each of these to a folder with their name)


now that you have all the files ready you can proceed:

(From BITMAIN's Control Board Recovery page)
3. Insert the Micro SD card into the card reader and connect to the computer.

4. Format the Micro SD card to FAT32

5. Copy the extracted file to the Micro SD card (Extracted from "L3+、D3、A3-SD Tools.zip")


RIGKING's FIXY-fixxer-son

6. Copy the files extracted from "Antminer-L3+-201708251737-384M.tar" to the SD card - Overwriting when prompted



Now continue following the directions from BITMAIN's support

6. Insert the Micro SD card into the control board

7. Power on the miner

8. Remove the Micro SD card after the miner gets its IP address


- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -


From this point, I was able to use the default credentials to log in, and flash the correct firmware

What am I missing? I've tried following this to a "T" using both the 2017 and 2018 firmwares, but no luck and stuck with 2019 firmware still

I did what rigking said and it saved my miner.

This said I would add 2 things:
- the SD card must be FAT32. It happens that my card was 64Gig, and therefore exFAT and not FAT. The miner was just ignoring it. I had to partition it, so I can format it using FAT32 and then follow rigking instructions to succeed
- After the miner booted on the SD card, I removed it and restarted the miner, which still had the 2019 OS on it. Therefore I did put back the sd card, booted, and then was able to flash a new OS (Hiveon) on my L3.

Note: I am still denied SSH, which may be normal (frankly I have no idea) with Hiveon asic software

Huge thanks to rigking for the links and the tip to overwrite with an old version...