iPhone 4 completely dead after update to iOS 7, anything to be done?

I have an iPhone 4 that I updated to iOS 7 today. Everything was going well; I'd been using the phone normally for a few hours. I was trying to add a picture of a friend from an iMessage to their contact card, and was at the point where I'd hit okay, and was just waiting for it to complete. It took longer than expected, but I just let it sit, and then my screen went blank and turned to this:

The lines are not static (they appear to be moving horizontally, but not vertically), the screen is flickering, and the phone is completely unresponsive. I have tried force restarting by holding down the home and top button for up to a minute, plugging the phone into the wall socket, connecting the phone to my computer, and nothing has caused even the slightest change. I can't even get the screen to turn off.

My question is basically, is there any hope of recovering my phone? Is there anything I can do now? If I just wait for it to die, is there a chance I can restore it?