General :: Built A Custom Kernel For Phone

I'm trying to make a custom kernel for the Samsung Gravity SMART using sources from the unofficial CM9 port for the Gio/Ace (which both use very similar hardware to the Gravity Smart). What I've succeeded at so far:

1) Acquiring the source, both for the CM9 kernel and for the stock Froyo kernel
2) Searching for the device-dependent references in the stock kernel
3) Porting those changes over to the CM9 kernel
4) Getting everything to actually compile
5) Acquiring the stock CM7.2 source
6) Creating device makefiles (i.e. BoardConfig.mk, etc)
7) Building CM7.2 using kernel built in step #4
8) Putting the various img files into an Odin-compatible .tar.md5
9) Actually flashing to the phone.

And for all that work, I got.. a soft-bricked phone (fortunately, I have an Odin file for stock firmware). The phone boots to a SAMSUNG logo (not flashing/throbbing). how the heck do I figure out what's actually failing? Is there a bootloader to unlock, and if so how do I unlock it?