There is a known bug known bug related to the Machine Learning in a Box desktop that we are investigating. The bug leads to a state where the Ubuntu log in appears and your password doesn't work.
Steps to fix:
1. Go back into the console and click on the Open Terminal Button (SSHing is fine too)
2. Type your password in the terminal,
3. Type cd /etc/X11/
4. Type ls
5. You should see a file named xorg.conf.20180319 (the numbers most likely corresponding to today's date) that had been renamed from xorg.conf
6. Rename the file by typing mv xorg.conf.20180319 xorg.conf
7. Type systemctl restart lightdm to restart X
8. You should now be able to log into the desktop