QidiFree - MCU bricked?

So I'm attempting to change over to vanilla Armbian/ Klipper, following u/ledustin's guide at https://github.com/leadustin/QIDI-up2date-english

No issues with KIAUH, nor with downloading, compiling, and flashing Katapult, nor with unmounting post Katapult flash. At least, no errors reported.

Here though is the problem - the MCU does not remount as a USB device, so /dev/serial does not exist, so I can't subsequently flash with Klipper.

Has anyone else encountered this? Does anyone know a solution? If I look in KIAUH, I can see that one MCU is detected, mounted at /dev/ttyS0 - but no more information