So I know there is already a very detailed tutorial out there that is quite good and safer than what I am writing, but a number of people seem to be interested in the method I discovered and have tested.
If you are interested in the safer(perhaps) way please look at this thread:
https://gbatemp.net/threads/how-to-...nofficially-without-burning-any-fuses.507461/

So the way I figured out basically sets up autoRCM or Brickmii right after the update, before any fuses can be burned. This is why this is potentially risky, if you do not boot into rcm after the update restart before the regular switch os boots the fuses will be burned and you will not be able to downgrade (at least without some other caveats)

DISCLAIMER: I believe this procedure is safe, but I take no responsibility if you somehow do burn fuses, get banned online, or other wise damage or break(brick) your switch console or connected hardware.3

NOTE: AutoRCM and Brickmii have a good chance of causing a small bug that prevents the system from staying powered completely off for more than 30 seconds, there may be a fix for this in the future. Also note that if your console boots to RCM without a payload device or computer sending it, it will appear to be off and can not charge, but will drain battery. I personal find this mildly annoying but most of the time I can keep it asleep in dock or powered on.

Also NOTE: this manner of updates may affect your cart slot firmware and may make the slot not read carts when loading an old fw version.

Things you will need:

• a rcm jig, or other reliable way to enter rcm (not autorcm or brickmii as they get removed during updates)
• A SX pro widget or similar product, or a realiable way to load a payload like sx os or hekate

Steps:

1. Back up everything (boot, raw nand, sd card, you can't be too safe) and keep it someplace safe and labeled
2. Check the fuse info using hekate, note how many are burned, so you know what you expect to see after the update
3. Boot up switch in OFW or CFW or even just plain with no mods or loaders
4. Once booted have your RCM jig inserted and ready to go ( be sure you have confirmed that this actually works)
5. using either a cartridge or updating via system settings (assuming you are comfortable going online, but I think this is safe) begin updating your system
6. *MOST IMPORTANT* When the update is almost done or the second you see the complete notification hold the [VOL +] button. And continue holding it till you get to hekate or sx os menu.
7. When the system reboots it should be in RCM mode, if you have a widget plugged in it should boot to SX OS or Hekate
   IF ON SX OS: navigate to tools and enable auto RCM.
   IF ON HEKATE: navigate to tools and enable brickmii.
8. Boot into CFW and you will be on the updated fw without having burned fuses
9. Feel free to use hekate menu to view the fuse info to confirm the fuses are in the same state.

Hope you find this useful.
P.s. I may post a guide on how to downgrade using backup, and a way to protect your cart slot fw as well in the future.

 

[deSSy2724]

Just wanted to update people who still want to attempt this:

It still works with the latest switch update.

Which bootloader do you use to boot your stock sysnand? The one from Atmosphere or SX OSs?

 

[chouitsu]

well good