If you have moved it to external storage then the plex database is located under the Android directory found in the root. Usually something like this:
/storage/ drivename /android/data/com.plexapp.mediaserver.smb/Plex Media Server/Plug-in Support/Databases
That is just the database and not the meta data.
PMS on Nvidia Shield- damaged database repair - Plex Media Server / Desktops & Laptops - Plex Forum
