QIDI X-MAX3 issues after update

Hello everyone,

this forum was recommended to me and I hope that i hit the right place to throw in my issue.

short backstory:
My company (IT & software development) got 2 3d printers for a relatively small project and since I'm the only one who ever worked with 3d printing, modelling and such (and therefore I'll be the one to maintain it) I was gifted one of them.
So I got my new toy home, plugged it in and did a few test prints.

But then I came across the web interface and there was a friendly little button showing me a notification that updates were available.
Of course I know about the importance of updates concerning security, optimization and qol so I hit the update button, but what's that? An error message pops up that I can not update?
Thankfully I have ssh available so I connect and run some apt update after fixing the repository and suddenly nothing works anymore because my klipper (EMMC) is now v0.12.0 and it's supposed to be "v0.10.0-530-g3387a9c2-dirty".

And that's where my journey begins... or rather ended...

current state:
The current firmware version for the X-MAX3 is 4.3.13 and after some time i got an EMMC adapter delivered and rolled back everything to the exact image that's currently running in the company yet neither with the "stock" image nor with the publicly available official "xindi-20230309" are working and whatever I try it keeps telling me "error" (yeah, thanks for the info...), but fluidd tells me something more specific:
"Internal error during connect: can't convert negative number to unsigned"

And the klippy.log says:

mcu 'mcu': Starting serial connect
Loaded MCU 'mcu' 124 commands (v0.12.0-175-g7b490f3e / gcc: (15:12.2.rel1-1) 12.2.1 20221205 binutils: (2.40-2+18+b1) 2.40)
MCU 'mcu' config: BUS_PINS_i2c1=PB6,PB7 BUS_PINS_i2c3=PA8,PC9 BUS_PINS_i2c2=PB10,PB11 BUS_PINS_spi3a=PC11,PC12,PC10 BUS_PINS_spi2a=PC2,PC3,PB10 SERIAL_BAUD=250000 RESERVE_PINS_crystal=PH0,PH1 CLOCK_FREQ=84000000 BUS_PINS_spi1a=PB4,PB5,PB3 STATS_SUMSQ_BASE=256 RECEIVE_WINDOW=192 BUS_PINS_sdio=PC12,PD2,PC8,PC9,PC10,PC11 STEPPER_BOTH_EDGE=1 BUS_PINS_i2c1a=PB8,PB9 ADC_MAX=4095 BUS_PINS_spi4=PE13,PE14,PE12 BUS_PINS_spi3=PB4,PB5,PB3 BUS_PINS_spi2=PB14,PB15,PB13 BUS_PINS_spi1=PA6,PA7,PA5 PWM_MAX=255 MCU=stm32f401xc RESERVE_PINS_serial=PA10,PA9
mcu 'MKS_THR': Starting serial connect
Loaded MCU 'MKS_THR' 112 commands (v0.12.0-175-g7b490f3e / gcc: (15:12.2.rel1-1) 12.2.1 20221205 binutils: (2.40-2+18+b1) 2.40)
MCU 'MKS_THR' config: BUS_PINS_spi0a=gpio0,gpio3,gpio2 BUS_PINS_i2c0h=gpio28,gpio29 BUS_PINS_spi0c=gpio16,gpio19,gpio18 BUS_PINS_spi0d=gpio20,gpio23,gpio22 BUS_PINS_i2c0b=gpio4,gpio5 BUS_PINS_i2c0c=gpio8,gpio9 BUS_PINS_i2c1c=gpio10,gpio11 BUS_PINS_i2c0a=gpio0,gpio1 BUS_PINS_i2c0f=gpio20,gpio21 BUS_PINS_i2c0g=gpio24,gpio25 BUS_PINS_i2c1g=gpio26,gpio27 BUS_PINS_i2c0e=gpio16,gpio17 BUS_PINS_i2c0d=gpio12,gpio13 BUS_PINS_i2c1e=gpio18,gpio19 BUS_PINS_i2c1f=gpio22,gpio23 BUS_PINS_spi1c=gpio24,gpio27,gpio26 BUS_PINS_spi1b=gpio12,gpio15,gpio14 BUS_PINS_spi1a=gpio8,gpio11,gpio10 STATS_SUMSQ_BASE=256 BUS_PINS_i2c1d=gpio14,gpio15 BUS_PINS_i2c1b=gpio6,gpio7 STEPPER_BOTH_EDGE=1 BUS_PINS_i2c1a=gpio2,gpio3 ADC_MAX=4095 PWM_MAX=255 BUS_PINS_spi0b=gpio4,gpio7,gpio6 MCU=rp2040 CLOCK_FREQ=12000000
Unhandled exception during connect
Traceback (most recent call last):
  File "/home/mks/klipper/klippy/klippy.py", line 180, in _connect
    cb()
  File "/home/mks/klipper/klippy/mcu.py", line 729, in _connect
    self._send_config(None)
  File "/home/mks/klipper/klippy/mcu.py", line 659, in _send_config
    cb()
  File "/home/mks/klipper/klippy/mcu.py", line 76, in _build_config
    state_tag), ffi_lib.free)
OverflowError: can't convert negative number to unsigned
webhooks client 281473212563752: New connection
webhooks client 281473212563752: Client info {'program': 'Moonraker', 'version': 'v0.7.1-609-gbdd0222-dirty'}
Internal error during connect: can't convert negative number to unsigned

Once the underlying issue is corrected, use the "RESTART"
command to reload the config and restart the host software.
Printer is halted

With my fixing attempts I did quite some stuff following different guides, but most of them were made for not exactly this model and I can't shake the feeling that I flashed my printhead at some point.

By the knowledge I've gathered so far you should NOT update a QIDI printer (a lesson that came to late for me), but it seems that the printhead now is running a wrong version.
So my approach would be reflashing that one, but for that I don't know what to configure in "make menuconfig" or how to actually get it onto the printhead.

I'm trying to fix this thing for almost a month now and also just ordered a replacement printhead controller board (if nothing helps, that might).
It seems that I have a newer version of the X-MAX3 with the X-6 board (not X-4) and a A-4 printhead board

Any help is greatly appreciated.

Knofel

Im having the same issue after I powered off my unit for the night and turned it back on i got abnormal start message, I had to restore the emmc, and did all their steps and now Im stuck at this point, I didnt custom or change anything accept update it to "Their" latest update.