iPhone 3G restore, cfw error 1600..ofw error1015

Hi,
I promised to my friend that I will unlock her iphone. Her iphone was really slow, so I choose"Erase all data, setting,.." And that was the biggest mistake..
I don´t remeber wich fw she had. But it was jailbroken.

Now, I want to restore her iPhone, but when I restore to official fimware(4.2.1) I get error 1015 in iTunes.

So I tried to put iPhone to pwnDFU mode and restore to snowbreeze custom firmware 4.2.1 and I got error 1600. I tried to delete apple.com line from host file, clear DNS flusch cache, tried another PC. But everything I have tried finished with same result- ERROR 1600.

She really needs that iPhone, and I don´t know what to do. Could someone help me?

Thanks
-BB007