How to install Android 4.4 on Samsung Galaxy S3 i9300


Important Note: The update is applicable to the SamsungGalaxy S3 GT-I9300 international model only. Using the steps on other versions may yield unfavorable or unexpected consequences so it is best to use the international model only. 
1.       Root the handset and install the ClockworkMod Touch 6.0.32. It is also possible to root or install it at a later time.
2.       Create a backup of all important settings, data and personal information. All files should have a back up to avoid problems. Do a manual backup instead of the option available on the Samsung Kies PC suite.
3.       Ensure the handset is 50 per cent charged or more to avoid problems because of power interruptions. The handset may have to use more power during the flash so it is best to have it charged.
4.       Allow USB debugging mode on the smartphone. To do this, go to Settings, choose Application, proceed to Development then select  USB "debugging" or "Settings" > Developer Options > USB "debugging."
5.       Install all required USB drivers for the Samsung Galaxy S3 GT-I9300 on the computer.
6.       Download the OmniROM 4.4 including PA Gapps to the computer. 
For flashing, follow these instructions:
1.       Connect the Samsung Galaxy S3 GT-I9300 to the computer through a USB cable.
2.       Copy both the OmniROM 4.4 and PA Gapps then transfer it to the SD card of the handset. Avoid extracting the zip files.
3.       Disconnect the handset and then turn it off.
4.       Reboot the handset to recovery mode. Do this by pressing and holding the power, home and volume up keys all together. Press and hold until the Samsung logo appears.
5.       Users can use the hard keys or touch controls to navigate while in recovery mode.
6.       Conduct an Android backup of the existing ROM on the handset. To do this, go to 'backup and restore > backup' to save the ROM. Users can restore anytime they wish to.
7.       Install the firmware along with the Google apps. Choose 'install zip from SD card > choose zip from SD card > look for the OmniROM 4.4 you have pasted earlier > confirm installation.'
8.       Follow the same step with the PA Gapps.
9.       Following installation, go to the main menu and choose "wipe data/factory reset."
10.   Reboot the device. Choose "reboot system now." Wait for around five minutes until the handset goes to the home screen. 
The device should be running on Android 4.4 KitKat. If the device proceeds to boot loop, users should reboot the handset to recovery mode. Do this by following these steps: 
- "wipe data/factory reset"
- "wipe cache partition"
- "advanced > wipe Dalvik cache"
- "install zip from SD card"
- "reboot system now" 
This should avoid the bugs found on the Android 4.3 Jelly Bean. 
Warning: The update is upon the discretion of the user. Providers of the update have control for what happens to the handset after. People can update at their own risk.