Whenever I try to turn on my iPhone 4S, it comes out with the Apple logo for a few seconds and then turn off.
Turning it on while holding the + button makes the iTunes screen appear. (The provided link is just an example - not my phone)
When I try to Restore and Update it, it extracts the software, starts to update and then suddenly and slowly fade away the Apple icon and turn off. Then it comes back to the iTunes screen again and the computer shows an unknown error 4013.
Yes, I did try another computer. Another USB cable. It simply won't work.
How can I overcome this?