my samsung vibrant is flashing the vibrant launch screen when i power on

[Dalton]

and wont go any further help!!!!? i rooted my samsung vibrant and downloaded a rom called blackhole boot animaation (blackhole.zip) it messed up my phone so i thought formatting the system would get rid of it but now when i try powering on my phone it shows the vibrant screen then goes black then goes back to the vibrant screen i dont know what to do i tried using odin but my phone wont go in to download mode please help!!!