Chose "overwrite" old files with .pacnew - now can't login

Use a live iso and open a terminal

sudo manjaro-chroot -a

Then check if you have these files

# /etc/shadow-
# /etc/passwd-

These are backups - list their content - they should contain your username

# cat /etc/passwd-
# cat /etc/shadow-

If they contain your username copy them to their original

# cp /etc/shadow- /etc/shadow
# cp /etc/passwd- /etc/passwd

Edit: 2020-09-01T05:40:00Z

Another candidate for verification is

  • /etc/group