I have two new iphone 3GS from the apple store. One beening 8gb and the other is a 16gb. One at 5.1.1 and other at 5.0.1. Serial # QR2100xxxxx and the other QR2060xxxxx. Apple replace it due to warranty issue. But now I need to unlocked it but I'm scare of brick my iPhones. I try to down grade the firmware to 4.1 pc and a Mac. Showing error 20.. Need some idea, 1) been how can I down graded it, 2) can I use the iPad baseband on the new baseband???