Unbricking a Lerdge-X board (the sequel)

A project log for Lerdge 3d Printer Mainboard Hacking

Breaking the encryption on the Lerdge series mainboards so I can try porting Marlin 2.0 to it.

J.C. NelsonJ.C. Nelson 12/21/2018 at 19:584 Comments

As I noted, I had overwritten my bootloader with non functional code. Having uploaded and let everyone else test the loader, it was time for me to do it, too. To do this, I needed to put the board into serial loader mode so the ST-Link would have time to get ahold of the chip. 

To do that, I pulled Boot0 high (connected it to the +3.3v from the ST-Link, which I'm using to power the board), and Boot1 Low (connected it to the middle pin on a sensor port.

I was immediately able to reset the chip, flash the lerdge base bootloader on, and get my beautiful "NO APP" Error message. 

This is 100% expected - after a reflash, there's no app on the board. If you wanted to move back to Lerdge's firmware, you'd proceed with a normal force update mode.


Bryan wrote 04/24/2019 at 12:13 point

ok so only have the the force.bin file in the firmware folder? Should I have the new firmware anywhere else on the sd card? The issue I'm having after putting the wrong firmware on it is when I power it on it searches for the lerdge k ui file path and since it cant find that path it errors out,so I'm stuck in this evil firmware loop. I'm not the best with software but am trying to learn as much as I can so this is all very much so over my head lol

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Bryan wrote 04/24/2019 at 00:39 point

I made the mistake of flashing the board with the Lerdge K 3.0.0 instead of the Lerdge X 3.0.0 firmware  but cannot figure out how to unbrick it. Can you please explain how to do this for us less fortunate folks who are unfamiliar with all of that craziness lol. I am so not familiar with all of this and need your help, if not ill be buying a new board

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J.C. Nelson wrote 04/24/2019 at 04:44 point

If all you did was update with the wrong firmware, a force update should work. To do that, take a nice, clean SD card and extract the lerdge-x firmware into it. You need to have a folder called /Lerdge_X_system/Firmware and in that, the filename should be Lerdge_X_firmware_force.bin. If you also have a Lerdge_X_firmware.bin, delete that (you want only the force one there). Put the SD card in and reboot.  The way I recall it, Lerdge's firmware zips already have the right structure, you just go in and delete the Lerdge_X_firmware.bin, leaving the force one. It should flip to the flashing screen and flash it right over. The X and the K are very similar hardware, so it should be possible to flash back.  

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cmshelton2010 wrote 12/22/2018 at 00:53 point

Thanks J.C. excellent work , you and your family have a great Christmas and New year holiday . 

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