How to compile a working kernel

Hi,
So I recently bought a Kobo Mini for tinkering, and I'm trying to compile a new kernel for it, since it is still running Linux 2.6.
I tried with NickelTC and the official imx507/KoboLabs sources, but that didn't work. The Mini only showed a blue light when powering up and nothing appeared on the screen. Even flashing the uImage that was already compiled in the tar.bz2 didn't work.
Am I missing something here?

Thanks. :)