What was found
AIRCRAFT POWERED WITH GPU RECEIVED A BATTERY EXCEEDENCE CAS MESSAGE. LIGHTS FLICKERED IN CABIN & A BURNING ODOR WAS NOTICED. IMMEDIATELY REMOVED POWER FROM ACFT & SHUTDOWN. VISUALLY INSPECTED NR 1 & 2 MAIN BATTERIES, NO DEFECTS. COMPLIED WITH BATTERY VOLTAGE CHECK, BATTERIES WITHIN LIMITS. STRONG ELECTRICAL ODOR IN THE COCKPIT. APPLIED BATTERY POWER, FAN FAIL CAS MESSAGE PRESENT & FAN IS NOT OPERATING. DISCONNECTED IESI CONNECTIONS FOR FAN ACCESS IAW MM 34-11-01. REMOVED AND REPLACED THE COOLING FAN IAW MM 31-41-07.