renaming your flashdmp to updflash doesnt make it your original nand rather it does nothing to it, obviously its still going to be the same modified kernel nand that it was when you dumped it from your modded console.

Your original nand should have been kept safe from day 1 of the mod install, you can however build a retail image if you have all your original files extracted.

I dont think he wants to flash his original i just think he wants to flash and old flashdmp that he wants to flash to his console