The Sam unit in these Smart cars is not just a fuse box but the central control unit for all the cars electrical systems. When these units fail it can be a very costly repair. Usually your only solution is to take your car to Mercedes and get them to supply and fit a new Sam unit, they then perform all the relevant coding to it to make it work. 4Smart can repair / refurbish Sam units and offer a replacement service at a fraction of the cost of a new unit.
Sam faults are normally due to the ingress of water into the electronics, a common fault on roadsters. To start with the SAM will usually only partially fail. Maybe your hazard lights, heater or electric windows will become intermittent or stop working completely. if you act quickly at the first signs of failure a repair is usually possible.