Get Android 4.1.2 Jelly Bean for AT&T Samsung Skyrocket SGH-I727

GUIDELINES to get Android 4.1.2 on AT&T Samsung Galaxy S2(SGH I727)  "Skyrocket" 

1. [Note] You might need to wipe the data on the phone to make the firmware boot up properly, especially if you flash it over a custom ROM. To be sure you do not lose any data, backup your Apps and important data — bookmarks, contacts, SMS, APNs (internet settings), etc. This Android backup guide would help you. The SD card contents are always safe, so there is no need to back up those. Only backup apps and personal data.
2. Download and install the software Kies on your computer, which will install the necessary drivers for the phone.
   Download Kies
   You can also download the drivers directly — download from here: 32 bit (x86) Windows |   64-bit (x64) Windows
3. Download the firmware.
   Download Link
   
4. Extract the file downloaded in step 3 on the computer to obtain a file named KIES_HOME_I727UCMC1_I727ATTMC1_844945_REV02_user_low_ship.tar.md5 (the file name may end at .tar, which is normal). This is the actual firmware file that we need to flash on the phone.
5. Download Odin. If you are new to this, Odin is what is used to flash stuff – firmware, kernels, etc. – on Samsung phones. We’ll use Odin to flash the firmware file obtained in step 4.
   Download Odin3 v3.04  |  Filename: Odin3_v3.04.zip
6. Extract the contents of the Odin3_v3.04.zip file to a folder on your computer. You should obtain a total of 4 files after extracting it.
7. Turn off your phone and wait for it to shut down completely.
8. Now, plug in your USB cable to the computer but not to the phone. Then, press and hold the Volume Down + Volume Up keys together, and while holding both keys pressed, connect the USB cable to the phone, then let go of the volume buttons. At the “Warning!” screen, press the Volume Up key to make the phone boot into download (Odin) mode.
9. Open Odin by double-clicking on the Odin3 v3.04.exe file obtained in step 6 after extracting Odin3_v3.04.zip.
10. Important! Connect your phone to PC now. You should get the message “Added !!” under Odin’s message box in the bottom left.
    • If you don’t get this message, make sure you installed drivers correctly (using Kies or directly) as given in step 1. If it still doesn’t work, try changing to another USB port on the computer and also use the USB ports on the back if you have a desktop PC.
11. Click on the PDA button in Odin, then browse to and select the KIES_HOME_I727UCMC1_I727ATTMC1_844945_REV02_user_low_ship.tar.md5 file obtained in step 4 above.
12. Do not make any other changes in Odin except selecting the required files as given in step 11. Leave all other options as they are. Make sure Re-Partition check box is not selected.
13. Now, hit the START button to start flashing the firmware on the phone. When the flashing is complete, your phone will automatically reboot — and when you see the Samsung logo, you can safely unplug the cable. Plus, you’ll get a PASS (with green background) message in the left-most box at the very top of Odin.
    • What to do if Odin gets stuck: If ODIN gets stuck and doesn’t seem to be doing anything, or you get a FAIL message (with red background) in ODIN, do the following – disconnect the phone from the PC, close ODIN, remove battery, re-insert it, and do the procedure again from Step 8.
14. [Note] After you get the PASS message and the phone reboots, the phone might get stuck at the booting animation. If that happens, perform the following steps to make it boot. Remember that these steps will wipe your personal data like contacts, apps, messages, etc. If your phone has already booted, skip these steps, your phone has been restored/fixed successfully:
    1. Boot to recovery mode — for which, first power off phone (by removing battery and reinserting it), wait for 5-6 seconds, and then press and hold Volume Up + Volume Down + Power keys together till the phone vibrates, then let go of the power button (but not the volume buttons) till the phone boots in recovery. Once you are in recovery mode, use volume keys to move the selection up and down and power key to select the option.
    2. Go to Wipe data/Factory Reset and select it. Select Yes on next screen.
    3. Then, select reboot system now to reboot the phone, which will now boot properly.
15. If you run into any roadblocks while flashing the firmware, let me know and I’ll help you out.

The Android 4.1.2 Jelly Bean update is now installed on your AT&T Skyrocket, and you can enjoy a faster and improved experience with lots of new features and enhancements. Please let me know how the process works  for you, in the comments below.