Struggling to flash unknown v853 board from 3d printer

[Fantomiaso]

Hello! My name is Dzmitry. I'm a 3D printing and robotics enthusiast from Belarus. I hope it won't be a problem that I'll communicate in English (it's the only language I know besides Russian). I'm hoping you can help me. Our community workshop received donated Infimech TX printers with a control board based on the V853 processor. Unfortunately, the 3D printer manufacturer provides extremely poor firmware—I'd even say dangerous, as the printers freeze and could potentially catch fire. I couldn't get any support from the manufacturer, so I tried to figure out the firmware myself. I'm not very knowledgeable about SoCs and Linux, so I'm hoping to get some help here.

I've already looked through guides on flashing this processor. I was pleased to see that the board has a USB port for flashing and a FEL button. I installed the drivers as described in this article:
https://v853.docs.aw-ol.com/en/study/study_5flash/
I also downloaded Phoenix Suite from there.

During driver installation, Windows warned that the drivers were unsigned, but they installed successfully. In Device Manager, a USB device appeared: "USB Device(VID_1f3a_PID_efe8)".

I wanted to flash the Debian image from this article:
https://bbs.aw-ol.com/topic/1699/固件-在-v853-vision-开发板上运行的-debian-linux?lang=ru

I put the board into FEL mode ("CCC" appeared in UART). However, Phoenix Suite doesn't detect any connected devices. I tried this on my Windows 10 computer (version 10.0.19045). I attempted disabling driver signature enforcement and running in safe mode. I even tried an old computer with Windows 7 and Windows XP.

The board also has a MicroSD slot, but the board doesn't detect the card (I flashed the card using PhoenixCard).

I'd like to create a backup of the EMMC memory before flashing a different image. I could do this by desoldering the chip, but I'm hoping there's an easier way. I'd also like to retain support for the RGB24 display.

I have attached the UART boot log and a photo of the board to this message.
log.txt
I hope you can help me!