How can I rebuild my installation after attempting to manually update D8 core using D7 instructions? After following the manual update instructions linked from the download page for Drupal 8.3.4, I got a "The website encountered an unexpected error. Please try again later." This is when I noticed that the breadcrumb for the update instructions said "Drupal 7".

As per the erroneusly linked instructions, I have deleted every file and folder in my drupal 8.3.2 installation except /sites, and I'm wondering what I need to do to restore them. Is there a reliable way to find out exactly which modules I had installed (e.g. translation files, or database tables?), and can I fix the problem by manually uploading the modules to /modules, or could the failed update.php job have damaged my installation?

(My server doesn't support automatic updates, and I only have FTP/MySQL access.)
Manually uploading the 3rd party modules to /modules (atleast the modules i found translation files for in my /sites folder) and restoring my database from backup, allowed me to restart the update process;  so far everything seems to be working again.