The USB Serial device listed looks like it could be the laser. Do you have any other devices connected that could be using the CH340 driver?
Do you see the laser listed in the ports list:
ls /dev/tty.wchusbserial*
If you haven’t already tried, disconnect all other devices other then follow this sequence:
- turn on the laser
- open lightburn
- Use Find My Laser or create manually. It’s possible that it won’t get auto-detected.