As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NO SATCOM PROMPT ON MCDU MENU PAGE. ACFT GROUNDED. PERFORMED FIM TASK 23-15-00-23-801, FOUND TRANSCEIVER IS IN THE LOCKED UP STATE. C4-(A) PERFORMED MANUAL POWER CYCLE TO RESET THE BOX. CYCLED THE SATCOM BREAKER P18-2, GRID D-14. RESET AND REBOOT SATCOM C/B D-14. POWER RESTORED AND PROMPT RETURNED TO MCDU MENU PAGE. OPS NORMAL. ACFT GOOD FOR RETURN TO SERVICE.