Galaxy S6 :: Samsung Phone Factory Data Reset On Its Own Then Lost Calendar Sync Performance

My quite new (3 weeks) S6 did a factory data reset on its own. It happened while I was driving for 2hrs on a highway, with the phone resting on the empty passenger seat, not touching the phone. Lost all data, all apps, all pics. Very frustrating. After 3 days of research (visiting Verizon store, calling Verizon, calling Samsung, internet research), the possible cause may the following:

About 2-3 hours before driving, the phone did a scheduled automatic update, which took more than 30 min to complete. This all happened in a signal-weak area. Tech support said, although the update completed, it may have had some flaws, and when the phone detects that, it may resort to a factory data reset to avoid greater functionality problems.

Unfortunately, the end result included functionality problems, most notably that the phone calendar only synched partially (!!) with my desktop Outlook calendar, and promptly I missed two important appointments.

When a scheduled update comes your way, make sure you backup all contacts, photos, data etc, before allowing an update to perform.