How to allow connection for edb database in Postgres
With PostgreSQL in general (not EDB specifically) you would do:


stop the PostgreSQL server
start postgres  in a shell in single user mode.
UPDATE pg_database SET datallowconn=true WHERE ... [to undo the error]. Be aware that template0 should normally be left with datallowconn=false.
Type Ctrl+D to quit the single user mode.
start PostgreSQL normally.