Boot issues recovery

If you messed up your file structure playing with your printer, you might end up (soft) brickign your printer. In my situation, my printer refused to start, only showing the Anycubic logo with an empty progress bar but nothing more. Some of the system files needed to start were missing, without any possibility of using SSH or ADB in software.

It is possible to recover from this situation and restore the partitions to a bootable state.

You will need to build a special USB cable and access to a Linux machine (Windows might work but neither confirmed nor documented yet).

Mainboard connection

Follow the guide on this page: Mainboard connection

Restore broken partitions

I uploaded a copy of working partitions to ease the recovery process. It uses 2.3.5.3 firmware and I deleted / changed all the device-specific keys, you will need to provide/restore yours in the files listed below (in the userdata and useremain partitions).

Link to partition backup:

https://rinkhals.meowcat285.com/

userdata partition

I managed to recover form a deletion of everything in the userdata partition. This one contains all the startup scripts for your printer to boot and to start Klipper, the UI, everything.

I took the last official update package (2.3.5.3 at the time of writing).

• Unzip the .swu file with this password U2FsdGVkX19deTfqpXHZnB5GeyQ/dtlbHjkUnwgCi+w=
• Extract the setup.tar.gz file
• There is a update_shell/update_udisk_init.sh script, responsible (I guess) to initialize everything from the update itself

I then modified the script to use the path of my partition being modified, and removed all the unecessary parts:

update_file_path="./update_swu"
to_update_path="./_userdata/app/gk"
to_update_wifi_cfg="./_userdata/wifi_cfg"
to_run_sh_path="./_userdata/app/kenv"

I ran the modified script, made sure all the necessary files are present, including specifically: