Locked out of iPhone iOS6 and in airplane mode?

I purchased a used iPhone 5 with iOS6 installed online for cash and can't use it. Here are the details:
-iPhone 5, iOS6 installed
-Phone is in airplane mode
-Phone has a passcode that I don't know

The guy I bought it from online won't answer/return my emails I feel like I may have been ripped off. I tried to restore it by holding the home button while plugging it into my iTunes, then it proceeded to restore it but halfway through I got an error message saying:

"there was a problem downloading the software for the iPhone. The network connection timed out. Make sure network settings are correct and your network is active."

Can I wipe the iPhone and restore it to factory settings a different way so I can use it? I think there's no connection because it's stuck in airplane mode.

Restart it