I have the same issue with my 7 Plus...Since I was able to see that there is a version 11.2 update; I am currently trying to process the 11.2 update. The phone has kicked itself out of the download update process 2x so far; nope 3x; nope 4x;
Decided to turn off some features. Turned off Background App refresh; turned off bluetooth;
I also have the Iphone 7plus PLUGGED IN.
Nope 5x and back to passcode re-entry; Restarted the software update for 11.2 for 6x -- the download is about 1/2 done per the blue progress line; it has progressed about 1/2 inch -- about a 1/2 inch left; I think the key here is patience... the update may actually be updating in the background even though the screen blacks out and we get the wherly derby spinning wheel.
Another few blackout cycles and now the Settings ICON has a RED 1 on it (indicating there is an update ready to install).
I tried installing it and the phone went to spinning wheel in about 10 seconds; second time it did it again; third time was the charm... the phone is now at the Black Screen with the WHITE APPLE with the update progress bar at about 40% point (note it took a couple minutes to get to this point) -- just set the stopwatch to see how long it takes to complete the update to 11.2.
It's been 2 minutes on the stopwatch (love my Fitbit)... the progress is at 50%. The screen just went back to a blank screen at about the 3:15 (minutes:seconds) mark, and then to the WHITE APPLE without a PROGRESS BAR... then the Progress Bar came up at a 25% level... the bar appears to be moving more quickly and is at the 80% point at about the 5:15 mark.
There has been no progress past the 80% point at the 7:00 minute mark. The update completed at about the 8:15 mark -- so that means the update to 11.2 took approximately 10 minutes to complete.
Just tested the phone really quickly... went to the CAMERA APP and successfully took a picture -- the phone previously went funky with the Black screen and Spinning wheel immediately when trying to snap the picture.
I will update this post if something unique starts happening to the phone similar to this issue.
Rick