Black screen on log in after update

Question

I'm running Ubuntu 22.04.3 LTS and have been for some time without issue.

Today I installed an update through apt as usual. It was a fairly large update to the latest version.

Now the laptop boots up fine, I can get to the login screen fine, but when I log in I get nothing but a black screen. If I use Ctrl + Alt + F3 and bring up tty3 everything is there, my account, my files, everything is intact, I just have no desktop.

I followed the advice here:

After upgrading to 22.04 screen stays at a black screen when logging in

But it didn't make any difference in my case.

For what it's worth my machine is a Lenovo ThinkPad E15.

Update: Well now this is interesting. I tried the nomodeset fix recommended in the answer above again and it has worked. However one thing I notice immediately is that I am now unable to change my screen resolution at all!

Update 2: I thought I'd try my luck, remove nomodeset and see if, having successfully logged in once, I might just be able to get everything back to normal. And what do you know, with nomodeset removed I can log in and if I go to the Screen Display tab in Settings, instead of monitor unknown I get built-in display and the option to change resolution is back. The option is back, but no setting other than 1920 x 1080 (16:9) works. Attempting to select any other option gives a black screen for about 30 seconds before everything comes back as before. Presumably on a very much related note, whenever I log in a message comes up advising me of a Device Firmware update. Specifically the update is for

ThinkPad L14 Gen2 / L15 AMD Gen 2 Embedded Controller Update 0 → 0.1.13.

If I press update it tells me the update has been installed but a restart is needed for it to take effect. Pressing the restart button does nothing and if I restart myself I get the same message on log in.