You can enable the debug output by maintaining START while the kernel is loading. It can provide useful info.
In your particular case, I believe the kernel starts but fails to load the root file system. Are you sure the file is named "rootfs.bin" ?
Note that if Windows reports it as being a BIN file, and not an unknown file, then you should name it just "rootfs". Windows has the nasty habit of removing the extensions of the files.