The Galaxy S3 LTE variant with the I9305 model number can now support custom ROMs and, here you can find instructions on how to successfully flash the Supreme Android 4.1.2 custom ROM. Read the entire tutorial and make sure that you don't skip any steps that I have listed. If your device is the I9300 model of SGS3 then you shouldn't use this tutorial to update it.

Leamoor, an XDA member and developer, is the one who released this new custom ROM for the I9305 Galaxy S3 LTE phone. It is built around the XXELKC Android 4.1.2 and it brings several tweaks and customizations. It is a stable ROM  and it features the Multi-Window feature, transparent notifcation menu and status bar, blue center clock and multiple other changes and functions.

Supreme ROM Android 4.1.2 is rooted using SuperSU, it is deodexed and zipaligned. Now, if you want to install it then you should read the guidelines below. These will help you correctly install this new ROM on your smartphone. Here's what you need to know:

  •  This guide works only with the Samsung Galaxy S3 LTE variant with the model number I9305. Do not attempt to flash this custom ROM on any other Android device.
  • Your phone should be rooted and running CWM Recovery. Without these, you cannot install any modification on your device.
  • Use CWM recovery mode and create a full NANDROID backup of your current ROM. This sets a restore point for your device in case something goes wrong and you cannot boot after installation.
  • You can create a list of installed apps or you can create SMS, Call Logs and APN internet settings backups using the following tools: SMS backup & restore | Call Logs backup & restore | APN Settings Backup & Restore | AppBack for Android application. Note that some of these apps will ask for root access.
  • Since you will have to wipe data from your device for this new ROM to work, it means that you have to sync your Contacts with your Gmail account. Here's a guide that teaches you how to do that.
  • Remember to charge the smartphone's battery until its power levels are saying that it is over 50%. This will prevent the device from powering off while you're flashing the new ROM.
  • Note that we cannot be blamed for any data loss nor, in case the device doesn't boot successfully after installation. This is a guide for advanced Android users.
  • Don't skip any steps listed below and you should be able to flash the Supreme Jelly Bean custom ROM on your SGS3 LTE.

These were all the guidelines that you had to read before starting to install the new ROM on your device.

How to flash the Supreme Android 4.1.2 Custom ROM on your Samsung Galaxy S3 LTE I9305:

  1. Download the custom ROM zip file from HERE. Save this file on your PC and don't extract its contents.
  2. Connect the SGS3 LTE to your PC using the USB cable. Now copy the Supreme ROM zip onto its internal SD card. When the file is copied, unplug the phone from PC and after that you need to power off the SGS3.
  3. Boot into CWM Recovery mode by pressing and holding at the same time Volume Up, Home and Power. Release these buttons when the screen powers ON.
  4. When you're at the main recovery menu, you can choose to create a Nandroid backup in case you didn't make one until now. Select 'backup and restore' option and create a ROM backup. If you already have such file on your device, skip this step.
  5. Select 'wipe data/ factory reset' option and then confirm this action.
  6. Now you need to select 'install zip from SD card'. From the new menu select 'choose zip from sdcard'.
  7. Find the Supreme 4.1.2 ROM zip and install it. When the ROM installs all its files, return to the main CWM Recovery menu.
  8. Select 'reboot system now'.
  9. The first boot process with the Supreme custom ROM starts now and it shouldn't take more than 5 minutes to complete.
  10. Enter your Google Account when the Android 4.1.2 / Supreme ROM welcome screen appears.
  11. That's it, you've updated your device and the only thing left to do is to test this new operating system.

In case the first boot process of this new ROM doesn't complete, you will need to power off the device and after that you need to repeat this entire tutorial. Sometimes, these custom ROMs will not install at your first attempt and that is why you should repeat all actions until you manage to complete the installation.

If you don't like how Supreme Jelly Bean 4.1.2 custom ROM runs on your Galaxy S3 LTE I9305, then you can use the backup ROM file, the one created before installing the new ROM, and restore your device to its previous OS. If you have any other questions, please leave them at the end of this article and we will try to provide you with our best answers.

jack · 6 years ago

it says update signature failed when chosing the file to install from the sd card?

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