Are you sure the battery is good? If it is, you'll need a multimeter and some familiarity with electrical circuits, so that you can interpret your car's wiring diagram and trace the current draw.
To reset the service indicator, ground pin 7 on the diagnostic connector and turn the ignition on for three or twelve seconds, depending on which indicator is lit. See http://www.unofficialbmw.com/e36/ele...ce_lights.html