I rewrite this tutorial from forum.xda-developers.com :
The users of Galaxy S III I9300 can now update their handsets to Android 5.0 Lollipop using custom ROM. The new Android 5.0 Lollipop comes with many new features :
- Up to 4x performance improvements.
- A battery saver feature which extends device use by up to 90 mins.
- It has a faster, smoother and more powerful computing experience.
- Support for 64-bit SoCs using ARM, x86, and MIPS-based cores.
- OpenGL ES 3.1 and Android extension pack brings Android to the forefront of mobile graphics putting it on par with desktop and console class performance.
- Responsive, natural motion, realistic lighting and shadows, and familiar visual elements make it easier to navigate your device.
- More intelligent ranking of notifications based on who they’re from and the type of communication. See all your notifications in one place by tapping the top of the screen.
- New devices come with encryption automatically turned on to help protect data on lost or stolen devices.
- SELinux enforcing for all applications means even better protection against vulnerabilities and malware.
- State of the art video technology with support for HEVC main profile to allow for UHD 4K 10-bit video playback, tunneled hardware video decoding to save power and improved HLS support for streaming.
- and other cool features.
Here are some more aspects that users should know before trying out the custom ROM :
- Users need to have proper back-up for their personal data on the phone.
- The handset should have at least 80 percent of battery power.
- The users also need to ensure that USB Debugging is enabled on the phone.
- During the installation, if the device gets stuck on booting, users can perform wipe cache partition and wipe dalvik before rebooting the phone.
1. Download Android 5.0 Lollipop ROM from link below :
The ROM File size is 128 MB, so I split the file into 3 parts :
ROM Part 1 : http://goo.gl/7pyL97
ROM Part 2 : http://goo.gl/ffHU2x
ROM Part 3 : http://goo.gl/l1zKh5
To combine 3 parts files above into 1 file just use WINRAR, then extract the files into ZIP format.
If any problem with the ROM, maybe because the ROM have corrupted during the download process, you can try to re-download the ROM.
2. Install the ROM Manager on your Galaxy S III I9300. Get it from Google Play Store, then install the clockwork mod recovery. You also can use ROM Installer application from JRummy Apps Inc.(Get it from Google Play Store).
3. Connect your Galaxy S III I9300 to your PC employing the USB information cable. Copy the “ROM.zip” file you downloaded to the SD memory card.
4. Restart your device in the recovery mode using ROM Manager. As soon as in Recovery Mode, go to ROM Manager and select backup/restore to back-up your information.
5. From the Recovery Menu do a total data erase (including Delvik Cache). When completed, go back to Recovery Principal Menu and choose Flash ROM from SD Card. Navigate the location you copied the ”ROM.zip” file and follow the directions for installing Android 5.0 Lollipop on your Galaxy S III I9300. As soon as the installation is over, just reboot your Galaxy S III I9300 device, and here you go, you’ve just upgraded it to the new Android 5.0 Lollipop.
Tutorial Video : Easy Way To Download ROM =