As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 2808 - EWR - FLIGHT CREW REPORTED THAT ON APU START RECEIVED APU FIRE INDICATION THAT CLEARED ITSELF UPON RE-START - APU RE-STARTED BUT ZERO AMPS. EWR MX PERFORMED FIRE DETECTION ON APU - NO FAULTS FOUND. MX REMOVED AND REPLACED APU GCU AND PERFORMED OPERATIONAL CHECK SUCCESSFULLY. ACFT WAS APPROVED TO RETURN TO SERVICE.