Downgrade Samsung Galaxy S4 From 5.XX to 4.XX

This tutorial is for educational purposes only and nothing more than a proof / representation of concept. The Non-Technical Technical Support or any of its sources is not responsible should your MyPhone My28S' situation worsen.

Semi-Bricked, in terms of mobile phones, means that your unit is no longer capable of performing the task it was designed to (perform) and that it is literally as good as a paperweight. Your mobile phone may still power ON and can still be detected by your computer when plugged to a USB port.

This article may also allow you to fix your Samsung Galaxy S4 that is:

• Doing a boot loop
• No longer accessible due to forgotten password / access pattern
• Stuck on boot logo
• (Doing) Other stupid issues

Files Needed

Here are the files that you need to complete the procedures in this article and put back you MyPhone My28S back to its normal working condition:

1. 
   Different Versions of Odin: odin.zip
   
   
   
   
2. 
   AP File: i9505XXUGNK2_Repack_XEF_@EDZAMBER.tar.md5.zip
   
   
   
   
3. 
   GNK2 Bootloader: Bootloader_GNK2.tar
   
   
   
   
4. 
   GNK2 Modem: Modem_GNK2_FULL.tar
   
   
   
   

The Flashing Process

1. 
   Install Kies. Just check Google for Samsung Kies and it should lead you to an official download site where you can get one. Samsung Kies will be the driver that will allow your computer to recognize your Samsung Galaxy S4.
   
   
   
2. 
   Run Odin and load "i9505XXUGNK2_Repack_XEF_@EDZAMBER.tar.md5" firmware into where it says AP (in Odin), and make sure to leave the Auto reboot option UNCHECKED.
   
   
   
   
   
   
3. 
   Shutdown your Samsung Galaxy S4.
   
   
   
   
4. 
   Hold VOLUME DOWN + HOME buttons for at least 5 seconds, then (while still holding the VOLUME DOWN + HOME buttons) - hold the POWER button as well. This should show you an option so you can set your Samsung Galaxy S4 to DOWNLOAD MODE.
   
   
   
   
5. 
   Connect your Samsung galaxy S4 to a working USB port on your PC, and click on the Start button of Odin.
   
   
   
   
6. 
   It will be a waiting game at this point. All you need to do is just wait for the your Samsung Galaxy S4 to download all the files that Odin will be transferring.
   
   
   
   
   
   
7. 
   Once done, it will show the word Pass in Odin, disconnect your Samsung Galaxy S4 from your PC but do not power it OFF.
   
   
   
   
8. 
   Exit Odin, and then relaunch Odin.
   
   
   
   
9. 
   This time, put GNK2 Bootloader into BL and GNK2 Modem into CP. Make sure your CHECK the Auto reboot option.
   
   
   
   
   
   
10. 
    Once done, the phone will restart. Wait for the Samsung logo to show up. Once you see the Samsung logo, shut down Phone and restart into recovery.
    
    
    
    
11. 
    From here you need to shut the phone down.
    
    
    
    
12. 
    Go to recovery mode. Kindly follow these steps if you do not know how to access your Samsung Galaxy S4's recovery mode yet:
    
    A. While the phone is OFF, press and hold VOLUME UP + HOME + POWER buttons. Your Samsung Galaxy S4 will power ON, and you will notice blue writings on the upper left corner of your phone's screen.
    B. As soon as these blue writings appear on the upper left corner of your phone's screen - release the POWER button but keep holding on the VOLUME UP + HOME buttons.
    C. Once you got into the recovery screen you may release your hold on the VOLUME UP and HOME buttons.
    
    
    
    
13. 
    Do the three (3) process shown below while on the Recovery Mode:
    
    A. Wipe factory reset
    B. wipe cache partition
    C. reboot.
    
    
    
    
14. 
    Wait for your Samsung Galaxy S4 and you should have your unit's firmware back to 4.4.2.

Reference(s) / Test Environment(s):

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1. Brian M's good old Samsung Galaxy S4.
2. Windows 10 64-bit.
3. https://forum.xda-developers.com/galaxy-s4/general/i9505-downgrade-5-0-lollipop-to-4-4-2-t3052472