For those looking to taste KitKat on their Galaxy S4 LTE (I9505) before it is officially released by Samsung, you can do so if you follow the guide below. While not a major overhaul, you should notice substantial changes, like full-screen album art, better keyboard layout in landscape and wireless printing among other things. Do remember though, this is only a test build and Samsung may add/remove features when the final build is let out. If you are okay with, wait no more and keep reading!
I. Before You Begin
1. Back up everything you feel is important before you begin.
2. Charge your device to 75% or more to prevent unwanted shutdowns.
3. Make sure you have the necessary drivers installed before you start. Installing Samsung Kies usually takes care of this.
II. Necessary Downloads
1. I9505XXUFNAD_I9505OXXFNA2_I9505XXUFNAD_OXX.zip [Download link available in this post (needs registration to view the link)]
2. Odin3_v3.09.zip [Download link available in this post]
III. Flashing XXUFNAD Firmware
1. Extract Odin3_v3.09.zip to a folder on your desktop.
2. From the extracted folder, double-click on Odin3 v3.09.exe to start the Odin tool.
3. Power down your device and boot it into download mode. To do this, press and hold the Volume Down + Home + Power buttons until you see the Android logo.
4. Connect your device to your PC using a compatible microUSB cable. If there are drivers being installed at this point, let them do so before continuing. Also, you should see the ID:COM field turn blue, indicating that the drivers are installed properly and you are ready to go.
5. Extract I9505XXUFNAD_I9505OXXFNA2_I9505XXUFNAD_OXX.zip to a folder on your desktop. You should now have four files in the extracted folder:
6. On Odin, click on the BL button, navigate to the location of BL_I9505XXUFNAD_481100_REV06_user_low_ship_MULTI_C ERT.tar.md5 and select it to load it on to Odin.
7. Click on the AP button, navigate to the location of AP_I9505XXUFNAD_481100_REV06_user_low_ship_MULTI_C ERT.tar.md5 and select it to load it on to Odin.
8. Click on the CP button, navigate to the location of CP_I9505XXUFNA5_373648_REV06_user_low_ship_MULTI_C ERT.tar.md5 and select it to load it on to Odin.
9. Click on the CSC button, navigate to the location of CSC_OXX_I9505OXXFNA2_549230_REV06_user_low_ship_MU LTI_CERT.tar.md5 and select it to load it on to Odin.
10. Under the Option section, make sure that only Auto-Reboot and F. Reset Time boxes are checked. Do not check the Re-Partition box, as you will brick your device!
11. Click on Start to begin the flashing process.
Once the flash is done and Odin says PASS! in green, you are good to go and you now have Android 4.4.2 on your device!
IV. Rooting the Galaxy S4 running XXUFNAD
If you want to root your newly flashed Galaxy S4, this post should help you.