Where is the database stored? On iCloud by any chance? I ask as you mentioned something about a wrong password. Take a peek on Page 12 of the Manual (and in Help) the note about putting DEVONthink databases in a cloud-synced folder.
This is definitely not recommended, the database should be closed and the volume unmounted in the Finder before unplugging or switching off the SSD. Did you try to copy the database to the desktop as suggested?
What’s the extension of the database? .dtSparse or .dtBase2? In the second case you could try this:
Select the database in the Finder, choose “Show Package Contents” in the contextual menu
Copy (!) the most recent Backup folder to the desktop
Copy (!) the Files.noindex folder into the copied (!) Backup folder
Add the file extension .dtBase2 to the Backup folder
Now you should be able to open the copied Backup folder by double-clicking on it. Afterwards use File > Verify & Repair Database (or even better, use File > Verify & Repair Database and File > Rebuild Database…) to ensure that everything’s fine.