IPhone 3GS won't reboot after Jailbreak attempt?

I have tried all day to manually put it in DFU mode and could not get it to and I found the automatic custom firmware in Redsn0w to get it to I tried that and the restored the phone with that created firmware it got halfway done and then an error popped up and the phone hasn't turned on yet I have tried holding the home and sleep button multiple times but the screen still stays black but my computer makes the connect and disconnect sounds though.

You may have bricked the device. There's nothing you can do if that happens.