These steps can only be carried out to completion if you created an ECC from your original NAND. If you used a DGX ECC (or a >14719 ECC PRIOR to J-Runner 0.3 (build 1)) then you won't be able to restore a stock NAND. However you can use the steps to build an RGH NAND.
This tut needs screenshots for completion, but in essence will talk you through creating a new NAND when all you have is the current one + ECC written to the first 50 blocks.
This is documented very well in the J-Runner Manual (p.26), however I will leave this here because it currently doesn't cover the use of a donor SMC or replacing the CB for consoles which use a non-standard bootloader (will add later).
You need the following:
The Dashboard version you were on before you lost the files!
NAND Dump with ECC/Xell written to it.
LDV Value (from XeLL - count the number of F's on lines 7 and 8 of your fuses).
Retail donor NAND from same board type (Clean SMC pack here)
1. Take the dump of what you have and load into J-Runner.
2. Add your CPU key.
3. Select Tools / Extract Files.
4. Grab the kv_dec.bin and smc-config.bin from 'output' and keep them safe. These are entirely console specific and will allow you to return the console back to stock if you needed to. If you have a trinity and there's an fcrt_enc.bin also extracted, grab this too.
5. Rename the SMC file from the link above to smc.bin - choose the one which matches your board (Thanks to stefanounick for this!)
6. Choose your existing dashboard version in the dropdown of J-Runner. This is important to get right as the existing bootloader (CB) version needs to match the last one you had working on the console. Read my roadmap for noobies to see the differences.
7. Select Retail from the bulleted options - you may as well build a retail NAND.
kv_dec.bin to kv.bin
smc_dec.bin to smc.bin
fcrt_enc.bin to fcrt.bin (if it extracted).
9. Copy kv.bin, smc.bin, and smc-config.bin to J-Runner\xebuild\data\ (navigate to this folder - you'll see other files in there like crl.bin, dae.bin, extended.bin etc). Copy fcrt.bin if it was extracted.
10. Select Advanced / Create an image without nanddump.bin.
11. You'll be prompted for your LDV - enter it here.
Hopefully it should be done. Write to your NAND and test your new retail image.
EDIT: I've collected a list of CB versions and their sequence numbers.
To cut a long story short, fuses 02 on XeLL tells you what CB will be accepted for the console to boot retail. The CF/CG fuses (lines 7 & 8) get burned every time you take a dashboard update, but the CB fuse may not, depending on what dashboard is being applied.
Fuse 02 will look something like this:
Fuse 02 : F0FF000000000000
To calculate the value, the significant value is the right-most 'F'. In the example above, it's 4 characters from the left so is sequence 4.
This will be tidied up later, but below are the CB versions per console and their sequence values for CB lockdown.
So if you had F0FF000000000000 as Fuses 02 and you had a Falcon board, then it falls in the 1>5 category and your valid CB would be any dashboard with 5770 as the bootloader. Cross check that against my RGH Roadmap for noobies and you'll see that 5770 is acceptable for dashboards from 8495 to 14699.
Similarly if it was a Trinity, then CB 9231 would be the target CB so any dash from 15572 to present (16203) would be fine to build. The list covers the most common CB values.