As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LT ENG GEN/IDG ON MCO-APU S/D GOING THROUGH 19K APU RE-START OK BUT CREW LOST CONFIDENCE IN THE APU FOR THE CROSSING. AIR TURNBACK, ELEC GEN OFF L EICAS ILLUMINATED, RESET AS PER CHECKLIST. EICAS RETURNED, NO HELP. REPLACED LT IDG PER MM ENG RUN ALL INDICATIONS NORMAL, NO LEAKS. REMOVED MCO AND PLACARD. APU FWD TO MCO MEL 49-11-01.