Robert> Also, keep in mind that NAND Flashes are not error free and
Robert> that they are at random places. Using dd (or other, OOB
Robert> supported util) to preload an image on other NAND flash than
Robert> it was dumped from is risky. Image might contain valid, live
Robert> blocks where NAND has faults.

Yes, I'm aware of that --- I am using dd for testing on my embedded
system, but when I do the actual manufacturing I will be using a
programmer which knows how to deal with bad blocks.

And after I tried the dd test, I checked the partition for bad blocks
and it has none.  So I know that bad blocks aren't the reason the dd
test didn't work.