As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MIA CREW REPORTED AUXILIARY POWER UNIT FAILED WITH RT INTEGRATED DRIVE GENERATOR ON PLACARD. FLIGHT RETURNED MIA LANDED WITHOUT INCIDENT. ACFT REMOVED FROM SERVICE. REPLACED APU LOW OIL TEMPERATURE SWITCH & RT INTEGRATED DRIVE GENERATOR, MPN 727792N. SYS GND CHECKED NORMAL, OPERATION CLOSED.