i had a little trouble with the updates on a fresh install when i installed on my main PC. During the update the screen would go black and be presented with a flashing cursor in the top left. I rebooted and continued the updates and everything was fine.
When i installed solus on my 2 brothers PC's, once at the login screen after install i would press
login in the terminal and run the updates there
Once complete reboot and all is well
Doing it this way you could probably get more detailed information on were it fails or what is happening.