Up for sale is a good used Saab 9-3 battery terminal circuit breaker.  This unit aside from being a battery terminal is a circuit breaker for the entire electrical system, connected to the positive cable.  This unit is designed to trip if there is a MAJOR electrical fault (i.e. large short circuit).  These units can fail in a manner that causes a disconnected battery, even though it is connected and properly re-set.  If you are having problems with this unit, often times it can cause a no-start, no electrical power condition.  You can diagnose this unit by making sure it is re-set, and then connecting an ohm meter across it's terminals.  If you read anything but 0 ohms, the unit is defective.  We just checked this unit, and it's in good working condition!