I will also tell you that we do theorhetically know how to flash the M0 chip via uart, there was a thread on here about a similar board being flashed that way directly from the pi, we could break the pins out of the board and then do it like that,
as the LPC chip that controls the tool head is the same as the BTT SKR 1.4 board we can use a similar settup as described here in order to flash the m0 chip, we’d just need to break out the pins needed and figure out the rest of that, fortunately we have the exact chip mode, AND BTT shows in depth skematics for their boards which will gtive us the info we need,