As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHEN THE NOSE TAXI LIGHTS WERE TURNED ON AFTER POWERBACK, SPARKS AND SMOKE CAME OUT FROM UNDER THE NOSE LIGHT SWITCH PANEL. AIRCRAFT RETURNED TO THE GATE. MAINTENANCE REPLACED THE NOSE TAXI LIGHT SWITCH. OPERATIONAL CHECK OK. AIRCRAFT RETURNED TO SERVICE.