As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TRANSFER OF POWER FROM EXTERNAL POWER TO APU GENERATOR. THE SATCOM NR 1 LIGHT ON THE P8 PANEL ILLUMINATED AND THE TWO-TONE CHIME RANG. THE SATCOM PROMPT ALSO DISAPPEARED FROM THE MCDUS. ACFT GROUNDED. PERFORMED POWER RESET WITH BATTERY AND EXTERNAL POWER OFF AND ON. SAT-COM PROMP CAME BACK AND SYSTEM OPS. NORMAL IAW AMM 23-15-00.