PocketBook 626 (Touch Lux 2)

[kukudas]

Hi everyone,
My PocketBook 626 (Touch Lux 2) has gone into read-only mode. The internal MicroSD card seems to be locked or corrupted.
I managed to open the device and tried flashing a new image onto a new MicroSD card, but unfortunately, I haven't been successful. The device still doesn't boot properly (or describe your exact issue here, e.g., "it stucks on the boot screen" / "it rolls back to old state")
Could someone please provide a known working clean firmware image for the PocketBook 626?
Here are my device details:
Model: PocketBook 626 (Touch Lux 2)
Serial Number YT4409004543002000Y6
Also, if there are any specific steps or tools (like Win32DiskImager, DD, or Linux specific commands) I should use to properly adapt the image to my device's serial number, please let me know.
Thank you in advance for your help!