This hypothesis fits most of the bill. Even the cracks were found near the antennas. The only thing is the low flying reports from Maldives, if reliable. But the plane would have pinged and flown on until given an new waypoint and if the FMC had been damages or was getting bad input it could have gone haywire and given waypoints that had recently been used that were in its memory.
Except that this aircraft didn't have the antennas that caused the cracks spawning the AD.