TLDR: I tried to install updates yesterday and now I can’t get past the login screen.

Linux Mint 21.3 on a Lenovo Yoga 370. I’m able to boot to live USB. I never got around to setting up Timeshift.

I was running the update manager yesterday, but admittedly just blindly clicking okay. Eventually the process completed and I rebooted, then went to check for updates again. This time, it was giving me an error message telling me to use the “Broken” filter. Reading some forum posts on the topic didn’t help me find this, so I tried again to install a few remaining updates, those failed, so I tried rebooting again. Now it boots up normally until an error saying, “unable to launch “cinnamon-session-cinnamon” X session — “cinnamon-session-cinnamon” not found; falling back to default session.” I click “okay”, then it brings up the log in screen. When I enter my password, it just goes back to the “unable to launch…” error message.

I’ve done some digging through forum results for similar issues, but haven’t found anything that works, just lots of dead ends and/or things that are well over my head.