These are instructions to wipe and reinstall OS:
1. Download and install Desktop Manager 4.2 from Here.
(Be sure that the BB is not connected during install.)
2. Download and install to your PC, the latest OS for your device from Here
3. Delete the file "vendor.xml" located in c:\program files\common files\research in motion\apploader.
4. On your PC, install JL_CMDER, located Here.
Connect the device and use JL_CMDER to wipe the device. Be sure that Desktop Manager isn't running when using JL_CMDER. When finished your device should display a 507 error.
5. Open Desktop Manager and run Application Loader. The Desktop Manager should then detect the device and load the new OS.
That should give you a clean, out-of-the-box device.