Just got my iPhone 5s at&t out of a blue screen boot loop how do i prevent this in the future?

My sister has had her iphone 5s at&t for a while. While using it would get stuck on the apple logo but would usually reboot and be fine within a minute. Today i just got stuck there and didn't go back to normal, so i decided to completely restore it (7.1.0) and after 10 tries of pluggin the usb in different ports and putting it in dfu and restore mode i finally got it to work. (9 of those tries it finished the restore then went into a blue screen and proceeded to show an apple logo with a loading bar that wouldn't move). Now i'm just holding on to it and probably going to take it to the apple store to get it replaced but it has no warrenty and im not prepared to pay 200 or more for a phone thats in perfect condition without a scratch(kidda stupid to charge a flat rate for every problem i understand if the phones glass is broken but for os problems). So is there any options i have rather than taking it to apple to stop this problem from happening.