nvidia is the default account in my serial console terminal after TX2 boots up. I am trying to make serial console auto login with a different user such as root or ubuntu or a user that I have created, but no success.
Have you tried substituting the name “nvidia” with the user you wish to use, e.g., “ubuntu”? Also, if you try to log in as any user than make sure manual login works with that user name as well before trying to automate it (e.g., “root” won’t be allowed on Ubuntu without special steps).
First, see what happens if you disable the file simply by using gzip on it and rebooting. If that doesn’t do what you want, gunzip the file, and then try editing the existing line with “–autologin nvidia” to remove that part of the line (and just that part).
I did a bit of research and it seems that once things hand off to Linux (U-Boot has its own mechanism) there is a config in “/etc/init/ttyS0.conf”. This looks like one of the old style init files, so it may be easier to edit than a systemd file.