Progress! Sort of. If I boot up the computer, and make my way to the command line via Ctrl Alt F4, then I can type “startx” and it will load the desktop! Found that here:
Only thing is, some things are still broken. Firefox won’t open, and neither will the terminal. Dolphin seems to be working fine though. I have to do that every time now, so something is still broken. Any idea what I need to do, in order to fix the problem permanently?