FTK opens without presenting any errors, but no cases are listed and all options are greyed out. Alternatively, FTK might list the cases, but give the error "This case is currently locked" when trying to open a case.
Follow the steps in this article to repair the PostgreSQL junction links.
One or more of the PostgreSQL junction links may no longer be working. This will be indicated in an error log in the "pg_log" folder (within the "pgdata" folder) that will say something similar to "could not open file "MDT ERROR: pg_tblspc/******/PG_*.*_******/******/******": No such file or directory".