As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ELECTRIC LIGHT ILLUMINATED AND STAYED ON AFTER GROUND POWER WAS PULLED PREMATURELY. ACFT GROUNDED. PERFORMED BITE CHECK OF ELECTRIC LIGHT MESSAGE ON P5-3 PANEL. FAULTED SPCU. PERFORMED SPCU RESET IAW FIM 24-34, TASK 802. SPCU FAIL MESSAGE CLEARED. ELECTRIC LIGHT EXTINGUISHED. NO CURRENT FAULTS NOTED. OK FOR SERVICE.