itunes error, itunes error 1600

I have updated my ios on iphone 3gs from 4.1 to 5..0.1 but after 3 months i got problem on my iphone. It turned power off suddenly and i can't reboot again.

Again i want to restore it to custom ipsw 5.0.1 but i am facing itunes error 1600. I tried iREB, Snowbridge and others to fix it but i couldnt. So please tell me the best idea that i can reboot and restore it to custom firmware.

Thanx in advance.