Help!

Here is my problem - I added my sister to my family iphone plan and gave her my iphone 4 and kept the new 4s that came with her account. The phone was updated to the newest software and working fine when I gave it to her. She went back home (I live in Seattle she in Portland) and after about a week she calls me from a friends phone saying the phone is broken and will only turn on when plugged in but just shows the cord and itunes logo.

Long story short after getting it back and taking it to an apple store they tell me it's been jailbroken and they won't do anything with it. I've never jailbroken any of my iphones and she won't tell me what she attempted (or a friend) to do. I've spent days on google trying everything to restore it. I've gotten it successfully into DFU mode so itunes will recognize it but when I restore after several minutes of "verifying with apple servers" I get error 1602. If I just plug it in without DFU my computer doesn't recognize it at all and the iphone screen just cycles a never ending white apple logo. It won't turn on at all without being plugged in to the USB cord.

This is very frustrating. I've canceled her account with ATT and returned the 4s - I'm now using my wife's old iphone 3gs and I don't want to waste my upgrade before the 5 comes out. Can you recomend anything I'm missing or is it just a paperweight now? I appreciate any advice on this!

 

I've tried both of those and I still get error 1602.

I can't take it to a genius bar because they say it was jailbroken.