Good news! I have been able to test the Firestarter V2 board and most functionality works (still have to test the laser/photodiode but don't expect trouble here). Progress was slow as I had to port the TMC2130 Arduino library to the Beaglebone. You can find the ported library here, it works.
A challenge was that with multiple SPI devices you have to acknowledge a command by setting and clearing the chip select pin. Although obvious, this took me quite some time as it was done automatically for the default chip select pin and I did not have the right settings which made it a confusing bug.
I left the laser scanner in the car during day hours. The car became so hot that the PLA became more flexible and the scanhead started to warp. It could be that the laser is still aligned as the plate was reinforced with a metal bar but it doens't look good.
I started a fork of BeagleG for the Firestarter V2 board. Making the board ready for BeagleG seems quite easy. I hope to finish testing soon and will then commit it back to the main branch.
The Firestarter V2 will then be able to run two firmwares; BeagleG and my Python fork of LDgraphy. This will bring me a lot closer to start making PCBs with a spindle and the Hexastorm :-).