Nickman I've read this thread 3 times and you have never said whether you could access a terminal. All this stuff that people are trying to help you with depends on your answer, whether it affirmative or negative. I usually do that crl+alt+FX thang when its rebooting, myself..not when it's still.
Nickman That doesn’t seem to be the problem, because I’ve had this computer for years with Solus on it and it’s never done this to me before.
Been there. First, partial updates of your choosing are a bad habit. But you assured you did a full one.
Second: I've had three Solus meltdowns like you are having (over some time). Two were my complete recklessness and ignorance.
The third was a year ago after an update forced the unholy marriage between the nouveau graphics driver and the lightdm display manager to explode in bitter 'uncoupling' and it took several fixes in the Live ISO and a Nvidia driver and 4 days of head-scratching (I'm really slow) to make it work.
I am stubborn and stupid and go for the salvage no matter the cost. I do not recommend this road.
Most people here are 10X smarter and ask themselves 'did I back up enough stuff to make a fresh install easy?'
Long story short: once you access a terminal then you know what your options are. Is it as simple as fixing some broken stuff, as stalebrim advised? Or restarting a serice? Or getting down and dirty in the live ISO?