Disconnected database files

I did not realize that when files were loaded to a database in Devonthink they were altered in some way that makes them inaccessible outside of Devonthink–it is as if they are all inside envelopes or something. I was unhappy with my database organization and thought that I could simply delete the database and start over, but now the actual pdf documents cannot be accessed without the original database functionality, or so it seems. How do I either reconnect to a new database in Devonthink or release the documents from the “envelope” or whatever Devonthink did to them when they were in the database?

As part of my backups, I do a weekly export of my files
Menu option File > Export > Files and Folders

The files are exported, along with tags and folder structure
and other metdata

reconnect to a new database in Devonthink

Files can be moved between databases

but now the actual pdf documents cannot be accessed

The files can be accessed
Right-click the file, and select Open With

Actually DEVONthink doesn’t modify files on its own, importing just copies them to the database package (.dtBase2). What kind of files did you use, what’s their file extension?