So I jailbreak ny iPhone 4 running Ios 5.1.1 a couple months or so and I loved it. But for my birthday I got a new phone and so I planned to sell my iPhone to a friend. Well I went through the process of restoring the phone by going into iTunes and restoring the device to a previous back up. And when it loaded cydia and all of my apps were still there even though all the content on my phone is from months ago. So I tried every single back up on my computer and all of them are the same. So then I put my phone unto DFU like some things online had said, and restored the device to factory defaults. But rather than the device actually restoring, I get an error message after iTunes downloads the software. I'm at wits end and I don't know what to do. I honestly just want to restore it to factory defaults so the phone is like brand new so I can sell it off to my friend. But I've tried every guide on the internet, and I'm not super tech savvy so I wouldn't necessarily know what to do on my own. So can someone help me?