First off test your sd card with h2wtest (may have mispelt) I recommend using fat32 on your sd
Use this
https://gbatemp.net/threads/newest-hekate-sdfiles-zip.506280/
Seems you'll have to download the atmosphere files here and install them over
https://github.com/Atmosphere-NX/Atmosphere/releases/tag/0.8.0
First step is to delete internet connection settings (any saved connections), then with a jig of your choice boot into rcm (make sure your switch is compatible here
https://gbatemp.net/threads/switch-...he-first-post-before-asking-questions.481215/ )
if you're unsure just try anyway nothing bad can come of it.
(here is a post on making rcm jigs, but I advise you use autorcm and just charge whenever you're not using your switch).
https://gbatemp.net/threads/the-ultimate-list-of-mods-to-enter-rcm.502145/
After rcm is loaded you need to push the payload with whatever program suits your needs.
I'm on windows and I use tegra rcm.
First thing to do is to load the hekate payload and dump all files, such as biskeys, calc files, boot files, and your nand of course (always back these up every time you update firmwares).
Then use 90DNs here
https://gbatemp.net/threads/90dns-dns-server-for-blocking-all-nintendo-servers.516234/ .
After that if you stay offline you'll stay unbanned and at any point can restore your nand backup and go online, rebackup your nand before you want to reenable cfw, then turn off internet and use cfw again and loop. You can now load any payload (such as the latest atmosphere) and use cfw.
I'd also grab the latest retroarch build from here and install. the nsp isn't neccesary, but if you go online anyway you'll be banned inevitably. Retroarch is a great aio emulator that uses various cores and is simpe to use, also has rewind and save states (and lots of other customization options)
https://buildbot.libretro.com/stable/1.7.5/nintendo/switch/libnx/RetroArch.7z (extract to switch sd card)
this is the optional nsp which will install an icon on the home menu to access retro arch
https://buildbot.libretro.com/stable/1.7.5/nintendo/switch/libnx/RetroArch.nsp
Can't link to any warez on this site, but this has some good stuff
https://www.switchbru.com/appstore/#/