Iphone 3g/3gs won't start.stuck up with apple logo?

Please help my iphone won't start it stuck up with apple logo then nothing happens. I already restore using itunes but nothing happen. Then i tried redsnow but it says that my iphone is not supported. Please help. And one more thing my iphone is like grey screen but i can still see the apple logo. What will i do to make it normal?

It might be dead try charging it other than that you would have to reset it via computer or rebuild it