As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CSS 1ST ATTEMPT FAILED AT FL 360 SAT -50 WITH A FAULT LIGHT. LIGHT WENT OUT WITHIN 5 MIN IAW QRH DESCENDED TO FL 340. APU STARTED AT -49 SEAT BUT APU EGT TOPPED OUT AT 960 DEG CSS PASSED. REPLACED APU ECU IAW AMM 49-61-12/401. APU STARTING AND OPS CHECK GOOD ON GROUND. APU BITE GOOD, NO FAULTS FOUND.