Stuck in recovery mode iPhone

I tried jailbreaking my new Iphone 3GS 32g with firmware 3.1.2 (05.11.07) with blackra1n.
During jailbreaking my iPhone was stuck in recovery mode. I was trying many times to restart blackra1n. And also I did try to restore with iTunes to 3.1.2 ,it's giving me every time the same message "This device isn't eligible for the requested build". So i stuck I recovery mode. Can u help me please, what I shoul do?