a) Install BlackBerry Desktop Manager on Your PC
b) Download and install OS of Your choice and remove vendor file from C:\Program Files\Common Files\Research In Motion\AppLoader
c) Remove the device battery
d) Connect the device to computer using USB cable
e) Open Desktop Manager -> Options -> Connection Settings
f) In “Connection” choose “USB PIN” and wait (it could take some time). If DM would not recognise the device – choose “Detect Device” option
g) Enter the Aplication Loader from main menu
h) Choose OS to install
i) Continue, until You saw “Finish”
j) DON’T choose “Finish” – choose “Advanced”
k) Ensure that both selection fields are marked
l) Continue untill DM ask if You want to make a backup file – choose DO NOT AUTOMATICALLY BACK UP MY HANDHELD
m) Instalation process should start now. Without disconnecting the device insert battery. Sometimes You have to wait with this until application shows information about connecting with device.
This process may fail sometimes so You have not to surrender and try few times – it should work.