Sorry dont mean to hijack your thread but I think I am having a similar problem - posted in the wrong spot before so hopefully I am ok here...
Have a Vibrant and some how got crossed up on it.
I have been able to use Odin to update the phone, however after it says its done, it does a reboot as it supposed to, shows the samsung screen then just shuts down.
After about a hundred tries, someone pointed me to Eugene's no brick. I tried that and it will fix it so it will boot and go into recovery, but I can't seem to do much once I get there. My only options are to update, wide data and wipe cache. Can't get to the point where I can load an update onto the unit.
I tried wide data and reset, then reboot. It shows the samsung vibrant logo, then the splash screen, then the big S and then screen goes black and the cap buttons stay lit.
If I try to go back and load the stock pit and jfd file, it just goes back to not booting at all and shutting down after the logo
I cant seem to get it into recovery unless I do Eugene's fix
In one of my earlier attempts, I did check to repartition as direct in one of the other threads - been chasing this a while now!
Edit: It was originally a bell phone - does this matter?