Once we have the .ipsw file I recommend moving it to the desktop to have it more at hand, to proceed with the downgrade we must connect our device to iTunes using the lightning cable, disable “Search my iPhone” and while keep the SHIFT button pressed (the up arrow) click on the button “Restore iPhone …”, after this we will open a drop-down that will allow us to search and select the “.ipsw” file previously downloaded or found, we must find it and click on “Open”, once this is done iTunes will proceed to restore the device with the selected iOS version .
It is important to mention the following details, the first is that when restoring we will lose all the data stored on our device, and the second is that we cannot restore a backup if it has been done with a more modern version, that is, you will not be able to restore a backup if it has been done since iOS 9.3, but it has been done since iOS 9.2.1.
The best accessories for your iPhone
Are you looking for a new case for your iPhone? An accessory for the Apple Watch? Maybe a Bluetooth speaker? Do not miss these offers on accessories and get the most out of Apple’s mobile: