I talked to my friend who had mod his iPhone and also a faulty center button. He said you can do resort to factory settings before sending in for servicing. I did not know if he did it. But I asked him if Apple service center notice his is phone is different since there is rumours Apple does a means to track. His reply was a resounding nope; they do not say anything/care/notice. He got his iPhone repaired few months back under warranty. After that, he mod again to latest version of iOS Hope this clear some issues some ppl have over jail-breaking.