The locked bootloaders on the Verizon Galaxy S3 do make it more difficult to make custom ROMs work on it (compared to other Galaxy S3 variants), but in the end the developers always make things work. Though quite late to the party, an unofficial Jelly Bean Android 4.1 custom ROM has been released for the Verizon S3.
XDA Recognized Developer incubus26jc has released an unofficial CM10 (CyanogenMod 10) ROM for the Verizon Galaxy S3. CM10 features CyanogenMod’s fast performance and useful customization options, along with Jelly Bean features such as a smooth and fast interface, actionable and more useful notifications, offline voice typing, Google Now (which provides info such as weather or traffic info without user intervention), advanced voice recognition, and more.
Important! There are a few points to note about the ROM as given below, which you should read before going further:
- The ROM is in its early stages of development, so a few bugs and issues may be present. Also, most Samsung specific feature such as popup play, SmartStay, etc will not be available as this is an AOSP/stock Android ROM.
- The ROM requires k-exec recovery to be flashed. After k-exec recovery is flashed, the phone will always reboot into recovery first, from where you will have to reboot again to boot into the ROM. This is a limitation of k-exec recovery that you will have to live with if you want to use custom ROMs like CM10 on it.
Now, let’s take a look at how CM10 can be flashed on the Verizon Galaxy S3.
This rom and the guide below are compatible only and only with the Verizon Galaxy S3, model number SCH-i535. It’s not compatible with other US variants or other devices. Check your device’s model number in: Settings » About phone.
The methods and procedures discussed here are considered risky and you should not attempt anything if you don’t know completely what it is. If any damage occurs to your device, we won’t be held liable.
How to Install CM10 ROM on Verizon Galaxy S3
Part I: Downloading ROM
- This procedure will wipe all your apps, data and settings (but it will NOT touch your SD cards, so don’t worry about those). Backup your Apps and important data — bookmarks, contacts, SMS, APNs (internet settings), etc. This Android backup guide would help you.
NOTE: Don’t forget to at least make a backup of your APN settings, which you can restore later if your data connection does not work after installing the ROM. Use the backup guide to find out how.
- Download the latest version of the ROM from its development page.
- Download the Google Apps package. This will install apps like Play Store, Gmail, etc. which are not present in the ROM by default.
Download Gapps | Filename: gapps-jb-20120726-signed.zip
- Copy both the downloaded files (ROM and the gapps file) to the internal SD card on the phone.
PART II: Backing up IMEI/EFS data:
The ROM needs K-exec recovery to be installed, which can sometimes erase the IMEI number/EFS data from the phone, resulting in the inability to make calls or use any network function like 3G/4G data, so we need to backup the IMEI first so we can restore it later if needed.
- First, root your phone by following the guide → here.
- Then, install Android Terminal Emulator from the Play Store (look for the app by Jack Palevich) on your phone.
- Run Terminal Emulator on the phone by clicking on the Terminal Emulator shortcut in the apps menu.
- Now, type in the following command in Terminal Emulator and press Enter.
After typing “su”, press the Allow/Grant button when prompted to grant Terminal Emulator root access.
- Then, in Terminal Emulator, type in the following command to backup your IMEI/EFS to the internal SD card.
dd if=/dev/block/mmcblk0p11 of=/sdcard/efs.sbn
- Your SD card now contains the “efs.sbn” file which is a backup of your IMEI. Connect your phone to the computer and save the “efs.sbn” file in a convenient location for future use.
PART III: Flashing K-Exec Recovery
Now we need to flash K-exec recovery which will be used to flash the ROM.
- Download the k-exec recovery image.
Download k-exec | Filename: d2vzw_recovery.img
- Copy the d2vzw_recovery.img file to the internal SD card on the phone. Send it directly to the SD card, do not put it inside any folder in the SD card.
- Open Terminal Emulator again. Then, type in “su” and grant it root access (as done in step 4 of part II of the guide).
- Then, type in the following commands to flash k-exec recovery, pressing Enter after each command:
dd if=/sdcard/d2vzw_recovery.img of=/dev/block/mmcblk0p18 bs=256k sync reboot recovery
- Now, the phone will reboot into ClockworkMod recovery. Move on to the Part IV of the guide right below, in which the ROM will be flashed on the phone.
PART IV: Installing the ROM
- Your phone should be in ClockworkMod recovery. In recovery, use volume keys to scroll up and down between options and power key to select an option.
- Perform a Nandroid Backup of your existing ROM, so that you can always restore it from recovery if something does not work out with this ROM. To perform a backup, select Backup and Restore –> On the next screen, select Backup again. Go back to main recovery menu after backup is complete.
- Select wipe data/factory reset, then select Yes on next screen to confirm. Wait a while till the data wipe is complete.
- Select install zip from sdcard, then select choose zip from sdcard. Scroll to the ROM file on the SD card and select it. Confirm installation by selecting Yes – Install _____.zip on the next screen. The ROM will start installing.
- After ROM installation completes, select choose zip from sdcard again, then select the gapps-jb-20120726-signed.zip file to install the Google apps package.
- After the Gapps package finishes installing, select go back then select reboot system now to reboot the phone to boot up into CM10.
- The phone might reboot into recovery again (due to the limitation of k-exec recovery), in which case simply select reboot system now again to reboot the phone into CM10.
[Important!] Restoring IMEI/EFS Backup:
After the ROM boots up, check the IMEI number on the phone in Settings » About phone » Status. If it is zero, then follow the steps below to restore your EFS data.
- Open Terminal Emulator (you might need to re-install it from the Play Store using a Wi-Fi connection).
- Type in “su” then grant it root access.
- Then, type in the following commands to restore the IMEI, pressing Enter after each command.
dd if=/sdcard/efs.sbn of=/dev/block/mmcblk0p11 reboot
- After the phone reboots, your IMEI will be restored and you will be able to use the phone without problems. The phone will reboot into recovery first, where you will need to select reboot system now to reboot into CM10.
Returning to previous ROM:
If you don’t like CM10 or would like to go back to your previous ROM, press and hold the power button and reboot the phone. It will reboot into ClockworkMod recovery first (again, due to k-exec recovery). Here, select wipe data/factory reset to wipe data. Then, select backup and restore then restore your previous ROM by selecting it from the list. After restore is complete, reboot the phone from the main recovery menu.
CM10, based on Android 4.1 Jelly Bean is now installed and running on your Verizon Galaxy S3. Visit the official development page for more info and to get the latest updates on the ROM. Share your thoughts on the ROM in the comments.