Be sure you selected the right blackberry model then download the latest OS file to desktop. There are unofficial versions (some call it leak version) of blackberry OS floating around the internet, do it at your own risk if you decided to use those unofficial OS.
Install Blackberry OS software into default location (Basically just click next until end during installation) If you’re using software version from a different service provider other than your own, after the installation wizard is done you will need go to delete the Vendor.xml file. It can be found following this path:
C:\Program Files\Common Files\Research In Motion\AppLoader
After the deletion of the Vendor.xml file (if needed), plug in your device to the computer via USB cable and then double click on the Loader.exe file in the same folder
Click next for the first screen, the Wizard should automatically detect the port and should display USB and your PIN number. Like screenshot below
Next the Application Loader Wizard will read your devices system configuration. System will allow you to choose any applications that you would like to install into Blackberry handheld. Here you need to make sure applications such as BlackBerry Attachment Service, BlackBerry Messenger, and 3rd Party Application boxes are ticked, and any other applications you want installed to the device and select ‘Next’.
Completing the Application Loader Wizard screen will come up next and and show you exactly what Applications are being installed. Make sure everything you want installed is selected and select ‘Finish’.
It is depending on Blackberry device and can take up between 20-45 minutes for OS installation. PLEASE DO NOT UNPLUG CABLE FROM THE DEVICE. THIS WILL CAUSE YOUR DEVICE BRICKED AND MAKE YOUR DEVICE IN DEEP TROUBLE. Be patient and wait until the Application Loader Wizard is states Loading Operation is Complete.
At this point, you can unplug your device and your device is restarting. Usually it will take long time for the first restart (approximately 12min). Enjoy the new Operating System.
