What did you do to get all LEDs on when your NSA stopped booting? I hope NAND chip is still alive?
You can try rootfs with linux-kirkwood-dt kernel and see if nand will be writable with that kernel. (or pacman -S linux-kirkwood-dt and reboot your device, you will have kwboot the device again).
Can anybody with NSA310 confirm that nand is writable with either linux-kirkwood or linux-kirkwood-dt kernels to make sure it isn't the kernel at fault?