Have you tried pulling up a console (e.g. ctrl+F2); I’m having a similar issue with the latest update on my laptop RTX3070, but it’s LightDM and Cinnamon crashing due to a crash in the nVidia OpenGL libs when resuming from sleep.
After I reset my user lockout (when it crashes, it also burns through all my login attempts for 10 minutes), I’m able to ctrl+f7 to get back to LightDM and login to my session, which then prompts me to restart Cinnamon (since it too crashed). So, it’s not totally locked up, just the graphics have crashed.