If you can get SATA boot working you can correct everything even without a serial interface. The advantage of the serial interface is that you can see what is the problem with the current kernel in NAND.
I am not sure but I think that the kernel from ingmar_k you have used just supports Ext4 rootfs partitions during boot.
I am not sure but I think that the kernel from ingmar_k you have used just supports Ext4 rootfs partitions during boot.