I have been trying to help my coworker update her phone but it won’t take . She has iPhone 6 and is trying to update to iOS 11 from 9.3 . Her phone has downloaded the update and we tried to install it but it always ends in error . We tried to delete the iOS 11 update and redownload it twice already but it still won’t take . She has 3 gig available on her 16 gig phone so Space should not be an issue since update needs 2 gigs. Any suggestions?