1)(Optional) Uninstall any previous OS from your PC.

2)Download OS to PC. Use Internet Explorer to do so, not Firefox or Chrome. (For leaked versions, the browser is irrelevant though.)
*If 100% certain you’ve previously used FF or Chrome on same PC to DL an OS successfully, feel free to use FF or Chrome again.

3)Following successful DL, run OS file to install OS on PC.

4)On BB, go to BBM Options, scroll down to Backup section. Ensure Remote Backup is enabled AND also conduct a Local Backup to media card.

5)Go through any 3rd party apps that have option to save settings to media card, and conduct Backup to media card from menu within each of these apps. (Examples: all Bellshare apps such as BerryBuzz & BerryWeather; QuickLaunch; Shao’s apps such as Wallpaper Changer & SixTools; Show Me The Images; etc).

6)Connect BB to PC. Open DM and backup device. Close DM.

7)(Optional) Use desktop program like BBSAK or BBMCP to backup 3rd party apps.

8)On PC, navigate to
•64-bit: Computer/C:/Program Files (x86)/Common Files/Research In Motion/AppLoader and delete file therein called Vendor.
•32-bit: Computer/C:/Program Files/Common Files/Research In Motion/AppLoader and delete file therein called Vendor.
(Optional/Recommended) Run BB Boss v2.2 or Shrink-A-OS/BBH+ Tool.

9)In same AppLoader file where you deleted Vendor, double-click on Loader to initiate OS upgrade. Follow onscreen instructions.

10)After OS install is complete, perform several physical battery pulls over first 1-2 days for OS to “settle in.” Perform first batt pull very soon after OS is installed.