Many users prefer OS 7.0 for its slightly better battery life and snappier performance on the 9900’s 1.2GHz processor. However, modern carrier updates prevent downgrading. An autoloader doesn't care about "downgrade protection."
To help you get your device up and running smoothly, tell me: blackberry 9900 autoloader
Ensure you have a working Micro-USB cable to connect the 9900 to the computer. Many users prefer OS 7
C:\Program Files (x86)\Common Files\Research In Motion\AppLoader Delete Vendor.xml : In that same folder, delete any files named vendor.xml Install BlackBerry Desktop Software on your PC to
If the device still boots and connects, you can use → “Device” → “Update” instead. But an autoloader is more thorough and works on dead/bricked units.
Most legacy BlackBerry autoloaders are compiled as Windows executable files ( .exe ).
Install BlackBerry Desktop Software on your PC to ensure all necessary drivers are installed.