"I tried to upgrade my iPhone 6 from iOS 9.3.2 to 10 through iTunes, but it stuck on iTunes logo when upgrading. What's on the screen now is the iTunes logo. The iTunes works fine, showing "updating iPhone software" and the process is stuck at about 25%."
Restoring or updating iPhone 6/6s/6s Plus with iTunes is easy, but sometimes things happen and your iPhone may stuck on iTunes logo. Which meaning you can’t do anything with it and the screen will show iTunes plug-in logo, identified by the iTunes logo and a picture of a USB cable.
When it comes to iPhone 6 stuck on iTunes logo during iOS 10 upgrade, you can try to restart your iPhone first. Press and hold the Sleep/Wake and Home buttons at the same time until you see the Apple logo.
If your iPhone still stuck on "iTunes plug-in logo" after restart. There is another free and easy way to fix iPhone 6/6s stuck on iTunes logo during iOS 10 update, by the use of a free iPhone reboot tool, Tenorshare Reiboot, which can get your iPhone back to normal with only one click.
Tenorshare Reiboot can fix all iOS stuck, including stuck on iTunes logo, Apple logo, black screen, recovery mode and other 50 stuck issues.
The software only has two buttons, "Enter Recovery Mode" and "Exit Recovery Mode", after connect your iPhone to computer via USB cable, Reiboot will automatically detect the status of your iPhone. If your iPhone is stuck on iTunes logo, and the "Exit Recovery Mode" will be highlighted. Just click the highlighted button, and your iPhone will back to normal in a second.
Strongly recommend you try the Tenorshare Reiboot, no need to restore your iPhone, just one click, your iPhone stuck on iTunes logo during iOS 10 update will be fixed for free.
By the way, if there is some problems to update iPhone to iOS 10, you can also try an easier way, with Tenorshare iCareFone, you can repair iOS operating system to fix iOS issues like iOS crashes, iOS damage and all other system stuck issues that can't be repaired with Recovery Mode.