Hit restore. It will download the new firmware. While it's downloading, unplug your phone.
Then once it's done downloading, check for updates.
If you're a dev then go to the dev site and get the GM seed. It has the same build number as the final 3.0 release.
None of the files that downloaded from the 3.0 links thread show up when you shift+check for updates.
None of the files that downloaded from the 3.0 links thread show up when you shift+check for updates.
Then go here:
https://forums.macrumors.com/threads/723059/
Download the firmware. Hold shift or option and click check for updates and select that file.