How to enable UART for A203v2 with TX2 NX

I have a Jetson TX2 NX and A203v2 carrier board. The spec sheet says there is one UART available (pins 8 & 10) but a simple loopback test is unsuccessful with minicom, echo, CuteCom. I have reflashed the .dtb file with console=ttyS0 removed and some other configs from the NVIDIA forums but no success. Is there any documentation, tutorials, etc. that show how to use UART on this custom carrier board?

I had a similar issue setting up UART1 on the TX2NX. Out of the box, the BPMP is using the UART on the 40-pin header for a debug console. So you need to disable that and enable the serial interface in the device tree for the linux kernel. This post explains it in a bit more detail:

I found the easiest way to make the changes is to use the dtc tool to decompile the existing dtb files, then make the changes then recompile them.

Hope that helps!