As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED SMOKE AND BURNING ODOR IN CABIN & COCKPIT WITH APU FAIL WHILE BOARDING. EMERGENCY EVACUATION AT THE GATE. MAINTENANCE INSPECTED AND FOUND APU INOP AND AUTO SHUT DOWN CAUSING SMOKE IN CABIN. MAINTENANCE REPLACED THE APU AND OPERATIONAL CHECKS WERE GOOD.