Procedure:
1. Download the following file from this link:
http://www.megaupload.com/?d=JP9ZG268
2. Unzip the file inside of a new folder on your hard disk
3. Double check if actually you have a “unlock” bootloader unit ready to flash a ROM (prerequisite). How do you do this? Turn off complete your unit then press and hold vol down key and turn on your unit until it show up a tag “Unlocked” upper left corner and under this tag show up “Fastboot” release the vol down key
4. Now press vol up key to enter to the “Fastboot” mode
5. A tag under Fastboot will show up as follow: “Starting Fastboot protocol support”
6. Now is time to run the magic, go to the carpet you just unzip the file and double press or run “clean_4.5.91_ATT” file
7. A new windows DOS windows box will show up, now just press any key to continue on each part of the process
8. Flashing System / Webtop / Preinstall will take a little longer (aprox. 1 minute each) so be patience and let the magic do their work
9. At the end of the process you will be ask to reboot your phone automatic.
10. Enjoy it!
PROS:
• This procedure will actually CLEAN complete your phone except your INTERNAL & EXTERNAL sdcards.
• At the end you will have a Phone running pristine images of 4.5.91
• You will ended with an automatic root system, you just need to install Superuser from the market after first boot, no more hassles looking for rooting options
• You will end with Official Mobile Hotspot working so no more APN hacks or third hands apk from the market.