help/6900 sprint (carrier is cricket)

[whitefatboy2k]

made a cooked rom for a 6900 sprint (cricket is carrier) and it took all of it and now the phone goes to the 1st splash page then the next but will not go no futher?........
i can not go anywhere...active sync does not reconize the phone now...becuz it is (off) even tho it is on the screen.....(i call to my # and goes to voice mail so i know the phone thru the system is off)..
i can get to bootloader(3 different colors on screeen but still can not load another rom........
there has to be a way to use bootlader to get back using atice sync and laod a smaller rom....
basic and then build....
maybe i put to muuch on the 1st cooked rom...but the phone took it all...
damm i am a newbie..
thanks for ur response and help........