In the middle of an iPhone update and my iTunes won't recognise my phone in order to continue to update. Can I stop the update now?

Neither the computer nor iTunes are recognising my phone and I've been working on his for an hour, I want to stop the update so I can go to bed, how can I do that? It's only at the stage where it has a symbol on the screen of the iPhone cable linking to iTunes

You can't stop it without breaking your phone.