JadeKris

I think now you should contact with Apple support.

This error is typically caused by attempts to downgrade the iPhone, iPad, or iPod touch’s software. This can occur when you attempt to restore using an older .ipsw file. Downgrading to a previous version is not supported. To resolve this issue, attempt to restore with the latest iPhone, iPad, or iPod touch software available from Apple. This error can also occur when an unauthorized modification of the iOS has occurred and you are now trying to restore to an authorized, default state. Very rarely this error is caused by a hardware issue and requires service. Solutions: Step1: Set your iDevice into DFU mode. Connect your iPhone to PC using the USB cable, please make sure that your iDevice is fully charged. Hold Home button and Power button simultaneously for 10 seconds till the screen becomes black, and then release Power button. Continue pressing Home button for fifteen seconds. You’ve successfully set iDevice into DFU mode if you can see an iTunes logo on iDevice’s screen. Step2：You’re suggested to backup...

Here is the tip for Error 14:http://www.3u.com/tutorial/articles/1104...-to-fix-itunes-error-14-after-installing-ios-10 And 3uTools has an user's group, I am in it:　https://www.facebook.com/groups/3uTools/

Flash you iPhone using iTunes or 3uTools