For the matter of your iPhone locked after update, you might remain perplexed despite much thought. You must wonder why an iPhone is locked after an iOS update and even can't accept the passcode even it is correct. Actually for this, Apple can not offer reasonable explanations as well. But it doesn't mean there is no way out. Here we collect 5 possible solutions from some who have ever experienced the same issue. Try them to get your iPhone back to normal.
Part 1. Force Reboot iPhone
When the issue of iPhone locked after update is faced, an easy and possible way that you can adopt to bypass the lock screen is to force reboot your iPhone. It is tested to be efficient in certain cases and worth a shot.
On iPhone 6s or earlier: Press and hold the "Power" and "Home" buttons simultaneously until the Apple logo appears.
On iPhone 7 or 7 Plus: Hold down the "Power" and "Volume Down" buttons at the same time until you see the white Apple logo.
On iPhone 8 or later: Fast press and release the "Volume Up" button. Repeat the operation with "Volume Down" button. Next, hold the "Side" button until the Apple logo shows on the screen.