iphone 4S restore error codes 2006 and 2001. what do these actually mean?

My son's phone suddenly stopped working. We connected it to the Imac using the USB cable and it came up with a restore procedure suggestion to resolved the issue. We downloaded the latest version of ITunes and then we followed the restore process. I then see a pop up error message:

The iphone "iphone" could not be restored. An unknown error occurred (2001).

So I disconnected from the IMac reconnected and re-ran the restore procedure. This time we got the same message but with a 2006 error code.

The phone is less than a year old (bought for Christmas). It has been taken care of with no scratches, bangs or drops.

1. What is happening and what do I need to resolve?
2. Is it something that can be fixed?
3. should it cost me (is this under warranty) to resolve / repair?

Hopefully someone can help.

Thanks

Paul