The basic rundown:
1. Dump retail NAND multiple times & compare. If they're identical move on to the next step. If they're different, check NAND wiring and dump until you have duplicates.
2. Create ECC from your retail NAND dump.
3. Write ECC to NAND. Unplug power from Xbox for 30-60 seconds. Reconnect power and boot Xell with DVD eject. (CPU Key retrieval)
4. Build new NAND in J-runner using your retail NAND dump & CPU Key.
5. Write the RGH NAND to the Xbox & disconnect power for 30-60 seconds.
6. Boot normally.
Again, this is just a basic outline.