If your phone doesn't want to boot up again after the update, it gets stuck in a black screen, follow this tutorial where we root the Galaxy SII with Odin and put an official Samsung Android 4 ICS on it.
Samsung Android devices such as Galaxy S2 or S3 come with a cool app called Kies Air, enabling you to connect via WiFi connection and manage them using a web browser.
At any given time you can reset your Nexus 4 smartphone to the factory default settings, meaning you will bring your phone back to the same state as it was on a day when you took it out of the box.