For those of you with a rooted AT&T Galaxy S5 and still have not updated to Lollipop, here’s how you can easily update to Android 5.0 Lollipop and also keep root. This method is preferred over flashing stock firmware as you will be able to keep root.
First, you will need to download FlashFire. To do that, first sign up for Android FlashFire G+ Community, then sign up for the beta FlashFire here. Once you do those two, open up this link with your Play Store app and you should be able to install FlashFire app.