hi, i have acquired 3 iphone 4s phones from local sales, etc that I got really cheap,, Ive never used one or have had one activated,,, other than too power it up to ensure it works,, anyways,, is there a easy way to tell if it has a good esn? also 1 has a pretty scratched up screen and I see places that fix them for like 30$, is this a screen that I could easily fix myself.... thanks