Hi, I would like to know how can I tell if my phone has a legit/official firmware from Apple. The reason why I asked this is because it upgraded the firmware to 4.3.5 like iTunes suggest and after upgrading it got into the loop stuff where you see an iTunes logo and a usb cable tip. Anyway I got out into that part by painstakingly googling for a solution. Now the phones back and loaded with 4.1. I downloaded the restore firmware in a site called felixburns something then used iReb to fix the problem. Now I want to upgrade to the latest firmware, well my concern is I don't want to have that loop stuff again. My iPhone btw is a 3GS. Thanks!