HTC Vivid users can finally rejoice. Ice Cream Sandwich has finally arrived on this HTC handset, thanks to our ever-reliable programmers at XDA Developers.

Modders have cooked up a flashable version of AT&T’s stock ICS update for the HTC Vivid, which includes stock HTC Sense 3.6.  Plus, the flashable ROM is pre-rooted, so there’s no need for you to root the phone again after upgrading to this ROM.

Take note that this is stock firmware, so all HTC and AT&T bloatware are inside.  If that’s okay with you, read on to learn how to upgrade your HTC Vivid to Android 4.0.3 ICS and HTC Sense 3.6.

Requirements

You’ll need a few things:

• A rooted AT&T HTC Vivid with S-OFF, unlocked bootloader, and with ClockworkMod Recovery installed.  These instructions are only for the HTC Vivid.  So, do not attempt them on variants of the HTC Vivid.
  • Need help with rooting?  See our guide for rooting the HTC Vivid.
  • Unlock your bootloader using HTC’s Bootloader Unlock tool at HTCDev.com.  Remember to keep your copy of Unlock_code.bin.
• Android SDK installed properly on your computer.  You’re going to need ADB and Fastboot, both of which are in the Platform-Tools component of the SDK.  Make sure you also add the SDK tools and platform-tools folders to the system path so that you can run adb.exe and fastboot.exe from anywhere.
• HTC USB drivers installed on your computer.
• Enable USB debugging on your phone (Settings > Applications > Development).
• Enable Fast boot on your phone (Settings > Power).
• Flashing this ROM will wipe your data, so make sure to create a backup.
• Fully charge your battery. This makes sure that your HTC Vivid will not run out of juice in the middle of the upgrading process.
• Pre-rooted, stock Ice Cream Sandwich OTA update from AT&T (VIVID_ICS_OTA_ROOTED_CWM.zip, 407 MB)
• HBOOT update file (Download PH39IMG.zip, 35.6 MB)

Instructions

Use these instructions at your own risk.  We shall not be responsible for any damage that these may cause to you or your phone, nor do we guarantee that these instructions will work under your specific circumstances.  These instructions are for educational purposes only.

1. Connect your phone to the computer via USB cable.
2. Copy the pre-rooted ICS ROM (VIVID_ICS_OTA_ROOTED_CWM.zip) to your phone’s external SD card.
3. Copy PH39IMG.zip to your phone’s external SD card.
4. Open a command prompt on your computer.
5. Enter the command (without the quotes) “adb reboot recovery” at the command prompt.
6. On your phone, once you see the icon with a red exclamation mark, press both Volume Up and Power buttons at the same time.  Your phone is now in recovery mode.
7. Once in recovery mode, create a Nandroid backup of your current ROM from Backup and restore > Backup.
8. From the main recovery menu, select “Wipe data/factory reset”.  Confirm wiping.
9. Select “Wipe cache partition” and confirm wiping.
10. Select Advanced > Wipe Dalvik cache and confirm wiping.
11. Select “Install zip from sdcard,” then “Choose zip from sdcard”. Browse for the ROM file and select it using the Power button.  Confirm that you want to flash the file.
12. Reboot your phone.
13. Reboot it into HBOOT mode by entering (without the quotes) “adb reboot bootloader” at the command prompt.
14. If you get a message on your phone asking you to apply the update, select no.
15. Relock your phone’s bootloader by entering the command (without the quotes) “fastboot oem lock” at the command prompt.
16. Reboot the phone back into bootloader mode by entering the command (without the quotes) “fastboot reboot-bootloader” at the command prompt.
17. Use the Volume keys to highlight “BOOTLOADER”.  Press the Power button to select it.
18. The phone will check for update files.  It ought to automatically detect PH39IMG.zip.  When the phone asks you to apply the update, select Yes.
19. Reboot your phone.
20. Delete PH39IMG.zip from the external SD card.
21. On your computer, copy Unlock_cod.bin to the same folder where fastboot.exe is located.
22. Reboot the phone again into bootloader mode as in step 15.
23. From the command prompt, unlock your bootloader by entering the following command (without the quotes): “fastboot flash unlocktoken Unlock_code.bin”
24. Reinstall ClockworkMod Recovery through one of the followingmethods:
    1. Enter the command (without quotes) “fastboot flash recovery” at the command prompt.
    2. Flash an updated PH39IMG.zip, as follows:
       1. Download the PH39IMG.zip update file from here.
       2. Copy the file to your phone’s external SD card.
       3. Reboot the phone into HBOOT as in step 15.
       4. When the phone asks for permission to apply the update, select Yes.

Congratulations!  You’ve successfully upgraded your AT&T HTC Vivid to stock, pre-rooted Android 4.0.3 Ice Cream Sandwich with stock HTC Sense 3.6 and with ClockworkMod Recovery 5.5.0.4.