As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE CLIMBING THROUGH FL280, THE RIGHT CSD OIL TEMPERATURE BOTH OUT AND RISE, WENT OFF SCALE HIGH. THE CSD WAS DISCONNECTED SUCCESSFULLY. SEVERAL UNSUCCESSFUL ATTEMPTS WERE MADE TO START THE APU. THE COM PROCEDURES WERE FOLLOWED AND THE AIRCRAFT RETURNED TO MSP WITHOUT DIFFICULTY. MAINTENANCE REPLACED THE CSD. THE BURNER CAN AND IGNITION EXCITER BOX WERE CHANGED AND THE APU STARTED NORMALLY.