Wow, you got a CM5 quickly!
I don’t have one, but I know at least one issue. It’s fixed in Add CM5 device tree files · nerves-project/nerves_system_rpi5@bec066a · GitHub, but that change has not been posted in a release.
You could build nerves_system_rpi5 main. You’ll need to comment out or delete the other nerves_system_* dependencies in the mix.exs to avoid a version conflict on another library.
An easier option to try is to mount the MicroSD card in your computer. You should see a bunch of .dtb files. Download bcm2712-rpi-cm5*.dtb from GitHub - raspberrypi/rpi-firmware: Firmware files for the Raspberry Pi · GitHub and copy them to that directory. I can tell already that they added more .dtb files than what I saw last November when I first looked, so that commit that I pointed you to above may be incomplete.
As a side note, the fact that you’re not seeing any output on the UART is normal when the device tree files aren’t there. If you connect the HDMI output, you should see more signs of life.
Let me know how this works! If it starts looking good, I’ll just make a release with the updates so it will just work for the next person. But hopefully I’ll be able to try out a CM5 soon too!
