As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SMF - FLIGHT 2576, AT THE GATE DURING ENGINE START, RECEIVED SMOKE IN THE CABIN AND A RIGHT AC PACK FAIL MESSAGE. REMOVED THE PASSENGERS FROM THE PLANE WITHOUT INCIDENT. MAINTENANCE PLACED THE RIGHT PACK ON MEL 21-51-1B. AIRCRAFT RETURNED TO SERVICE. MAINTENANCE REPLACED THE RIGHT AIR CYCLE MACHINE AND THE RIGHT PACK DISCHARGE SENSOR. OPERATIONAL AND LEAK CHECKS GOOD. AIRCRAFT RETURNED TO SERVICE.