Pls visit Samsung Experience Store at BestBuy if you have tried 3+ hours without any clue. They have a tool to recover your phone to Android 4.3 within 20 min.
It's free even they know it might have been rooted. I'm saying so because I just had mine recovered. Good luck.
Search your local BestBuy to see if there is a Samsung Experience Store inside. As they are working for Samsung, and not BestBuy; your S4 doesn't have to be purchased from BestBuy so long as it is within warranty.
Best Buy Store Locator: Store Hours, Directions, Events & More
It's free even they know it might have been rooted. I'm saying so because I just had mine recovered. Good luck.
Search your local BestBuy to see if there is a Samsung Experience Store inside. As they are working for Samsung, and not BestBuy; your S4 doesn't have to be purchased from BestBuy so long as it is within warranty.
Best Buy Store Locator: Store Hours, Directions, Events & More