As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
MAINTENANCE FOUND APU FEEDER CABLES BURNT AT TERMINAL BLOCK S3-23 STA 148 WHILE TROUBLESHOOTING PLACARD ON APU. TWO SECTIONS OF APU FEEDER CABLE WIRE WERE SPLICED FROM STA 220 UP TO TERMINAL BLOCK S3-23 IAW MM 20-50-01. THE TERMINAL BLOCK WAS ALSO REMOVED AND REPLACED.