If you start a broker and the database isn't available, the broker will eventually "start" and then never retry to connect to the database again.  In this state, the broker process is running but not connected to a persistent store and also does not accept connections, and will remain this way indefinitely.

One solution is to extend the login timeout (e.g. SQL Server loginTimeout), but perhaps it would be better to make the MAX_SETUP_ATTEMPTS configurable?  Or shut down the broker process when it reaches the above state?