Before I got my current iPhone 8 in august 2018. I had a iPhone 6 that suddenly went to activation lock. It was Late August 2018 when it happened. I couldn’t get pass the lock so I had to replace my phone. To this day I don’t know how it happen in the first place. I’m always worried that it could happen to my current phone so I’m trying to figure out the cause to give me a piece of mine. I have some theories

The first theory was that it happen because I didn’t update my phone for a while and it suddenly it updated without my permission. I had just plug it in to charge it since it was dead and somehow when it restarted, it automatically began updating. I heard that it wasn’t uncommon that people who got the update got locked too.

The second theory was it was caused by find my iPhone. Maybe my mom accidentally marked it as lost(my phone was hers before she gave it to me).

The third was that it was a result of when i accidentally broke the screen a couple of earlier. It was repaired and was working fine but maybe the software glitch out from the breakage or the resulting repairs.

Could of any of them been possible or was something else?