Mike were do you buy your screens?
Must say I have fixed 1000s of iPhones and never did I once have to restore for phone to work. Obviously there is something wrong in the way you are installing the parts plus blue or red screen indicates the wrong screws in the emi Sheild and tearing traces below the screw holes. Hopefully this is not the case but you might be hearing from your customer sooner than later
Have a read
[http://www.iphonebits.co.uk/iphone-5s-blue-screen-solution/]