Hey so I am new to this forum, and i am looking for a solution to fix my iphone 4s. The issue I am facing is that my iphone 4s doesn't want to restore. The problem is I keep getting an error (21). I tried to change the battery and that didn't work. I have tried to look for special software and came up with nothing. At one point the iphone was showing the apple logo but it was looping continuously (very fast, maybe 5 seconds). So what is going on with this thing?