A few days ago, my iPhone stuck in a black screen. It was ON, I could use Siri, and every call or message were entering ok. Also, when toogling the silence switch, the iPhone vibrated.
I realized that it happens every time the display goes to a sleep mode (with power button, locked iPhone). Even though I use assistive touch to lock it, it happens the same. I wait so the auto lock triggers the locking, it happens the same.
In addition, recently I discovered some issues with the camera app. When trying to take a photo, it just show a blurred static image from the context. When switching to video capture, it gets fixed and now I see what I intend to capture. Now when I go back to photo capture mode, it shows well but I can't switch among cameras (front, back side). In video capture mode I can switch among cameras perfectly.
I already made (like three times) a full restore, using iTunes with the most updated software (iOS 10.0.2). I also chatted with apple support. I'm able to see the log files in my mac, and I see several kind of errors (I don't know if they are common or unusual).
My guess is ambiguous: - It may be hardware issue with the flex of the display or some kind of connector inside. But in that case I think the iPhone would go black randomly, and not only after locking it. - It may be software issue: I didn't find another person with an iPhone SE suffering my same problem. After a full restore, and updating to the latest software, any kind of software problems shoud have been fixed at this time.