I've recently tried to upgrade the OS on my 8310. I've tried downloading a variety of different carriers' software, but the O2 one (linked in the sticky topic above) always gives me the message: Error reading setup initialization file. I've tried downloading the file more than once.

So I've also tried older versions with other carriers, deleted the vendor.xml file (I'm on Orange) and when I run the Loader program it tells me my upgrade has been successful, but it's taken about 1 minute and nothing (visible) has changed.

I have gone to Options>About to check what OS I currently have.

Will changing the OS allow me to use any sim card? (i.e. will it unblock my phone?)

What OS does the device show?

Are you plugging in via a HUB or directly into the PC?

Did you try a battery pull on the BB?

Changing the OS will not unlock the phone. You will need to get an unlock code from your carrier or from some who specializes in unlocking such as Horizon Wireless Online, one of our sponsors.

OS: v4.5.69 (Platform 2.7.0.72)
Plugged into a PC via USB...

On the phone to T-Mobile about unblocking it now, cheers.

Any suggestions on how to update the OS?

Thanks