Manjaro ARM locking up after entering password for user on login screen - but root can login

Question

Prelude

• New to having a Linux distribution as an OS on anything I own.
• Brand new to any Linux OS with a GUI.
• Searched here on U&LSE, found questions that were tangentially similar, but nothing exactly. Closest to my issue was Manjaro: Can’t log in. Screen freezes after I enter my password, but things mentioned in those answers did not exactly seem to pertain.

Setup

• Laptop: Pinebook Pro
• Linux Distribution: Manjaro ARM (Pinebook Pro came with it installed)

Play-by-play

• Everything seemed to be working fine. I've been using this laptop daily for a few weeks with no major issues.
• Was logged in, mostly using web browsers
• Did a mass update of Manjaro and "gazillions" of other items that the system indicated needing updated.
• Some time after everything updated, used Ark to extract an archived folder to the desktop. This is my file that I archived and I have extracted folders exactly like this from that file at least a half-dozen times with no issues.
  • The extraction failed (don't recall the error)
• Got a popup which stated that Plasma crashed/died (don't recall specifics)
• Clicked [Pine button] {like the [Window] button or the [Apple] button (or whatever the button is on a Mac)} + L to try to lock the screen, intending to click Restart from the lock screen
  • Got a popup which stated that locking crashed/died/failed/would not work (don't recall specifics)
• Held down power button to shut down

Issue

• On power up, as usual it went to my main (and only) non-root user login screen
• Able to enter password
  • After entering and clicking 'Enter', nothing happened
• Able to move cursor (I use the track pad), but clicking has no effect
• Just sits there indefinitely

Further Info

• After holding down power button to shut down again, and then starting back up, if I don't enter a password I can click on "Restart" or "Shut down" and they work
• I can also click to log in as a different user
  • I am able to log in as root

Postlude

If it is possible for someone to know how to fix this issue directly, I'm all for it. As a "Plan B", I just need to retrieve some files from my user account and save them externally; then if I need to, I can wipe the machine and start from scratch (I would need to be pointed to help for that, though).

Answer 1

I assume that this is a rookie issue, but for folks like me who are rookies and don't already know all of this:

tl;dr

I was out of disk space.

Details

• As stated in the question, upon power up or reboot the GUI login screen would appear but would freeze after entering the correct password.
• If I tried this before freeze up, I was able to use Ctrl+Alt+F2 (or Ctrl+Alt+F3 or Ctrl+Alt+F4 or ...) to open a TTY/virtual terminal/however-it-is-properly-referenced and log in that way. [I had to discover that I could even attempt to do this, as I was unaware before trying to research my original issue.]
• Using this terminal session, I was able to find the files that I wanted to "save".
• I began trying to figure out how to mount my external drive in order to move said files.
• At some point, an attempt to create a new directory (or maybe copy a file locally) failed with an error that mentioned being out of space.
• After ultimately mounting my drive, copying files, and unmounting my drive, I locally deleted one large directory of files.
• Upon restart, I was able to log in via the GUI login screen

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So while most seasoned Linux users might have known the issue immediately, without something explicitly telling me when trying to log in that I was out of space, I had no idea - hence my question.