Take the phone to your carrier and ask if they could please reflash the update. And if that doesn't fix it, if they could please make it work, since the phone was working before the update, so it's their problem. (The update is guaranteed from the date of the update, regardless of whether the phone is under warranty or not. If the phone is too old for the new version of Android [I've heard that one a few times], it's their fault for sending the update to the phone, so it's still their liability.)