IPhone 3GS stuck in Emergency Call?

So, my friend has an iPhone 3GS. It's stuck in the Emergency Call screen and iTunes won't recognize his iPhone.
Now, I know about DFU mode. Only problem is, his power button is broken. Y'know, the button on the top of the phone, which is required for DFU mode (at least I think it is).
Please, I just want to help him out. Is there any way he can fix this?

You can try taking the battery out of the phone and re-turning it on. Not sure, try taking it into a store and see if they can fix it. If not I'm sure you can order a new phone if it's damaged or not working properly.

I don't know. But this shouldn't be in the education section. Just saying.