As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON PREFLIGHT, BOTH PACK LIGHTS AND ALL 3 ZONE TEMP LIGHTS ARE ILLUMINATED. APU IS RUNNING AND SUPPLYING BLEED AIR. ACFT GROUNDED. FOUND CIRCUIT BREAKER HOT AND TRIPPED. INSPECTED BREAKER AREA, NO DEFECT NOTED. RESET CIRCUIT BREAKER IAW AMM 20-60-01. PFM DC SYS TEST IAW AMM 24-31-00. NO DEFECT NOTED CIRCUIT BREAKER REARMED IN. ACFT OK FOR SERVICE.