Here's an update on my friend's iPhone. He took it in to the service dept., and they called back later telling him that his phone was toast. They couldn't recover his data or anything.
I'd be interested in finding out what happened with the OP's phone.
As was suggested earlier, it could have been a hardware issue that just happened to show up after the update. However, I can't help but be a bit skeptical. I also note that my own phone has stopped reminding me to update to that version of iOS. Is it possible that they've found their update is bricking some phones, and they've withdrawn the update for those specific phones?
BTW, I found this:
https://discussions.apple.com/thread/7956950?start=0&tstart=0It appears that a number of people have been having this problem.
