Android™

CyanogenMod 10.2 (CM10.2) Nightly ROM was recently released for a number of Jelly Bean devices which include Galaxy Note 2 N7100, Galaxy S4 I9505, Sony Xperia Z, HTC One X ,Galaxy S2 I9100 and S2 I9100G. Among them , the latest device to receive Android 4.3 based CM10.2 custom firmware is The Galaxy S3 LTE variant (GT-I9305).

The release is an Android Open Source Project (AOSP) based one , which requires the pre-installation of ClockworkMod (CWM) recovery . As the CM10.2 Nightly ROM works without the installation of Google Apps (GApps) , their installation is optional.
IBTimes UK provides you with the step-by-step guide for the installation of Android 4.3 Jelly Bean on Galaxy S3 GT-I9305 through the CyanogenMod 10.2 Nightly ROM.

Courtesy : XDA Developers

Using CynogenMod 10.2 Nightly ROM for the installation of Android 4.3 Jelly Bean on Galaxy S3 (LTE) GT-I9305 .
Plug in your phone to the computer and mount its SD card via USB cable.
Copy the Google Apps zip and downloaded ROM files to root folder on phone’s SD card without extracting them .
Remove the USB cable from the computer and switch off phone once the file transfer process is done.
Press and hold the Volume Up, Home and Power buttons to Boot the device in recovery mode . Wait for the screen to flash and then release all three buttons.
Take Nandroid backup of current ROM so that the data can be restored if the new ROM fails to work or if you feel the original ROM better. For a backup, choose Backup and Restore and then click Backup option displayed on the next screen. Once the backup is done ,return back to main recovery menu.
Perform a full data wipe task as follows: Choose Wipe Data/Factory Reset and then click Yes on next screen for the confirmation .It takes some time for the completion of the data wipe process. Now click Wipe Cache Partition once you return back to the CWM recovery main menu. Wait for the completion of the data wipe process . Under Advance options , Choose Wipe Dalvik Cache.
From the SD card , Chose the Install Zip option and then select Choose zip option from the SD card. Browse to CyanogenMod 10.2 unofficial ROM zip file copied to phone in Step 2 and select it by tapping Power button. Confirm the installation of ROM by choosing Yes on next screen and immediately ,installation will begin.
After the ROM installation, and repeat the previous step. Now ,Choose Gapps zip file to for the installation of the Google apps.
Once the installation of Google Apps is finished , return back to the main recovery menu and click reboot system now. The phone now reboots to the newly installed CM10.2 Nightly ROM. Leave the device along as the first boot may take some time.
Returning to Previous ROM
For the restoration of previous ROM , boot into recovery mode, choose Backup and Restore and restore original ROM by selecting it from list.
The update of Android 4.3 CyanogenMod 10.2 Nightly ROM is now successful on the Galaxy S3 GT-I9305 . For the verification of the firmware version installed ,Go to Settings -> About Phone .