Sprint 955i Won't Start

Morning All

I've had a look at the "Sprint won't start" thread but can't see anything that matches my problem. My 2002 Sprint 955i won't turn over on the starter button but I can start it by putting a screwdriver across the terminals of the starter solenoid. I've been told this means the starter motor is ok.
The wiring diagram in the Haynes manual shows that horn and rear light relay are on the same circuit. The horn isn't working but the rear light is. Does anyone know the fix to this problem?