can't logic with serial


I have just flashed avg xavier emmc with jetpack 4.2.2 .
I did not try to connect display or keyboard.
I try to do everything from serial terminal
But the problem is that I can’t login.
Trying user:nvidia pwd:nvidia or user:ubuntu pwd:ubuntu , both fails.

Please help,

You have to create the login account name/pass on first boot (it was only in the R28.x or previous releases whereby the account name/pass was pre-installed). Can you flash again, but with a serial console connected during the flash such that upon first boot you’ll be able to see steps for completing login name/pass?