Oh I get it now. You need to use the
-D option with minicom to get it to bind to a specific device otherwise it defaults to something else. Try this…
minicom -b 115200 -8 -D /dev/ttyACM0
I do NOT use the sdkmanager specifically because of issues like this. Nor do I use Windows. I’m using Fedora32 but the instructions for Ubuntu should be exactly the same. I have used both flash.sh to flash an entire NX and I’ve also written the sd card image directly to an sd card. Neither had issues with headless setup.
On the serial console (via the UART pins on the front panel header) I get this…
[ 6.526140] rtk_btusb: fw name is rtl8822cu_fw
[ 6.534152] rtk_btusb: This is not 8723a, use new patch style!
[ 7.766635] Please complete system configuration setup on the serial port provided by Jetson's USB device mode connection. e.g. /dev/ttyACMx where x can 0, 1, 2 etc.
I can then see a new /dev/ttyACMn device on the host and can connect to it using minicom, putty (for linux), cu, etc.