Connect the beaglebone to a monitor and keyboard.  Boot up.

In the earlier versions of the kernel, the system booted into X (the gui), and you were logged in as the debian user.   You would type ctrl-alt-F5 to get to a terminal login (this is quicker).

In later versions of debian, the X system is not installed by default.  You should see a full screen with a login prompt.  Use debian:temppwd to login.

Type uname -a to determine your OS version.  When you look for beaglebone tips on the internet, be aware that there are huge differences based on kernel.  This blog is based on 4.14.71-ti-r80 (stable version) kernel.

Set the root password with sudo su (use temppwd as the password).  Type passwd and enter the desired root password twice.

Switch directories to /etc/ssh, and edit sshd_config with nano.  Change the line “PermitRootLogin prohibit-password” to “PermitRootLogin yes” and restart sshd with “service ssh restart.”  This will allow you to ssh into the box as root using the new root password.