Jailbroken phone will not boot. Please help!

[cnet26]

I used blackra1n to jailbreak my phone. I then used it to install cydia and rock. I chose backgrounder to install and it downloaded then asked to reboot. The phone shut down, a few seconds later the apple logo popped up for about 20 seconds then went black. When I try to power it up the same thing happens. I have searched for about an hour and can't seem to find anything to try. PLEASE help.

[battlecrushr]

Put in dfu mode and restore. Then rejailbreak here's how dfu mode

How To: Enter DFU Restore Mode - ModMyi - Wiki

[Piazza331]

Do you have a 3G S? It's possible you have the new boot rom that requires you to run blackra1n every time you restart the phone.