Also it depends on what was the Nemo filesystem image you installed
Some images work immediately correct, some need a second boot to show up the UI.

And just as peterleinchen says, if the screen is dark just stick in the USB connector, set up your USB network connection as 192.168.2.14/24 and you will be able to ssh to the Nemo as root on 192.168.2.15. From the console you can then say "reboot" and next boot you should have the UI show up correctly.