Anyway, the warranty can be restored but only if you downgrade / update your handset with an official release of the Android system — only manually
because on rooted devices the OTA updates can't be received or flashed.
Because of the up mentioned aspects, here is what we can conclude by now: the warranty of your Samsung Galaxy S4 will not get void by updating to official Jelly Bean 4.2.2 XXUAMDL OS; also you don't need to have a rooted smartphone because you are not flashing a custom ROM; but in case your device is rooted, then after performing the steps from below, the root access will be revoked (you will be able to unchain the system of your handset by applying a new root guide that is suitable with the new XXUAMDL software); finally if your SGS4 is currently running on a custom OS, now you will be able to restore the stock Jelly Bean firmware and also you will be able to restore its wa
Because of the up mentioned aspects, here is what we can conclude by now: the warranty of your Samsung Galaxy S4 will not get void by updating to official Jelly Bean 4.2.2 XXUAMDL OS; also you don't need to have a
rooted smartphone
because you are not flashing a custom ROM; but in case your device is rooted, then after performing the steps from below, the root access will be revoked (you will be able to unchain the system of your handset by applying a new root guide that is suitable with the new XXUAMDL software); finally if your SGS4 is currently running on a custom OS, now you will be able to restore the stock Jelly Bean firmware and also you will be able to restore its wa
because you are not flashing a custom ROM; but in case your
device is
rooted, then after performing the steps from below, the
root access will be revoked (you will be able to unchain the system of your handset by applying a new
root guide that is suitable with the new XXUAMDL software); finally if your SGS4 is currently running
on a custom OS, now you will be able to restore the stock Jelly Bean firmware and also you will be able to restore its warranty.
Generally, unrooting with SuperSU is the best choice
on devices with a modified / system partition,
because all the changes that are done during the
rooting process are cleaned up.