I got a non working iphone from my friend. Well the screen cracked , but it still works and there are lots of scratches (big ones) at the back. I saw in amazon that they sell the parts for the iphone 1st gen If i buy that, then should i be able to take things out, then put everything back with the new parts?? Will there be any risks?? Is there anywhere that fixes it if i bring my iphone with the new parts i will buy??