As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WITH APU OPERATING, ELEC LIGHT ILLUMINATED ON OVERHEAD. PERFORMED BITE TEST STATIC INVERTER 1 INOPERATIVE. DURING APU SHUTDOWN, APU SHUTDOWN IMMEDIATELY AFTER SWITCH WAS PUT TO OFF. ACFT GROUNDED. TSR ISSUED. REPLACED SPCU REF MM 24-34-11-400-801.