steps for repair HDD

Hi All

I see many write steps to repair hdd

1- nand erase all
2- write sn
3- extract boot file
4- write

but as i see when i do nand erase all , extract boot file give error because it is already erased.

so do i need to do extract boot files first before i do nand erase all ?
or this option not needed at all , just write SN and other data