Alien Respawn Killed my 17 R2

I'm in a heap of trouble.  Short version:

My daughter's May/2015 Alienware 17 R2 (~6 years old, Windows 10) crashed and kept giving a "PNP DETECTED FATAL ERROR" when it rebooted (except it would boot in safe mode).  After trying a number of things, including System Restore (see below), I finally tried Alien Respawn.

After a couple hours, it said it had restored the OS.  But when I rebooted, it said, "The operating system couldn't be loaded because the NLS data is missing or contains errors" (error code 0xc0000242).  Now I can't even boot in safe mode.

At this point, I'd be satisfied with being able to get in there and back up some files before I completely reinstall (which Respawn promised me I'd get a chance to do).  I don't have a recovery USB or disc, although I have another Windows 10 PC that I could make one from.  Anything I can do?

Long Version:

This started ~3 days ago.  The laptop had been on and she was logged in, but when she went back to it after being AFK, it was at the blue Recovery window (with choices "See advanced repair options" and "Restart my PC").  Restarting caused it to go through BSOD three times and then back to the Recovery window.

First thing I tried was System Restore.  There was one restore point, from 3 days earlier (no system changes that we know of), and restoring it seemed to work.  But at some point when she was AFK, it had apparently crashed again and was at the Recovery window.  I did the System Restore again, and she baby-sat it all evening (interestingly, not letting the screen saver come on for any length of time).  It never crashed.  She shut it down, and the next day it still booted up and let her log in.  But when she left it alone for a period of time, it crashed again and wouldn't reboot (same symptoms, same error).  So it seems like the System Restore "fixed" something, but whatever it was would get broken again (maybe when the screen saver was running?).

I ran the diagnostics in the BIOS - no problems.

Here's where it gets strange.  The next day, we tried System Restore again, but it failed with an error (sorry, I didn't record it).  After that, the restore point was gone!

I booted in safe mode (took a while to find it) with no networking and let her log in (we both have admin accounts but I wasn't sure I remembered my password).  I couldn't figure out anything to do, so I rebooted in safe mode with networking, hoping to be able to update the drivers (which I found out today that you can't do in safe mode).  It seemed to work normally, but I knew I needed to research more of what to do.

This morning, I did the "thorough" disk diagnostic in the BIOS - took a couple of hours, but no problems found.

Now it gets more interesting: since my daughter was at work, I booted in safe mode (with networking), remembered my password, and logged in.  Windows immediately starting installing an update - and showing those calming, full-screen messages like it shows when you first install Windows 10 (although I felt a cold chill when it said, "Leave everything to us").  After that, it logged me in, but some things didn't work.  I couldn't type in the search bar, the Windows button didn't seem to work, left-clicking on the Start icon didn't do anything, and although right-clicking brought up a menu, about half of the items were inoperative (although I found other ways to open most of the things I needed via msconfig).

With very few options left, I rebooted and tried Alien Respawn.  The second step (scanning the files) took a really long time, and the third step (repairing the files) took over 2 hours.  But it said it was successful, so I rebooted. And I was greeted by this window:

This really ticks me off.  Before trying Respawn, I was still able to do some things.  Now I can't even transfer files.  I can't find anything on that error code, or even what NLS data is.

If I use a recovery USB to boot, will it give me access to the C: drive so that I can copy off things?  Can I use a recovery USB made from a different Windows 10 PC?

If you've actually read this far, thanks for your interest!

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John