Need help downgrading

Hello everyone.

Like and idiot, I updated my Mariko Switch to 11.0.1 before checking whether SX Core supports it or not.
I updated through ChoiDujour correctly (chose ExFAT with my memory formatted correctly) and update went smoothly.
Of course, it shows black screen afterwards and I'm royally screwed but then Atmosphere got updated to support 11.0.1 which is awesome.

I've tried to boot with Atmosphere payload in order to downgrade but it still gets stuck at a black screen.
Would someone kidlndly explain to me (duh-duh proof highly appreciated) what's my best course of action to regain functionality?

 

I'm very grateful for your comment but I didn't understand half of it (that's kind of the reason why I use SX to begin with -didn't require much knowledge-).
Would you kindly explain it in steps?

 

I'm genuinely thankful for your support, you gave me a point on where to start.
I never used anything other than SX so I'm completely oblivious on how others are used or why.
I'll get right on it.

 

I've been into a spiral of guides following one after the other fails.
Hope this works and very thankful for your help.

 

I finally got the time to try this method (off day) but it returned with the same error I got from other methods:
"Unknown pkg1 version.
HOS version not supported!
or emuMMC corrupt!
Trying backup bootloader...
Found pkg1 ('pG pG ~').

Unknown pkg1 version.
HOS version not supported!
or emuMMC corrupt!

Failed to launch HOS!

Press any key..."

Pressing power returns to Hekate menu.
Any idea how to proceed from here?
I have access to multiple working Switch units in case I could salvage any needed files.

 

Both.
I tried importing an SX emuNAND and creating a new emuMMC using Hekate.
Both gave the same error message.

 

I did but I don't recall the specific error I got.
I tried it both from SX boot menu and Hekate.

 

Sadly yes, didn't work but I don't recall the error I got.
And I apologise for the late reply as my phone was temporarily broken (disconnected from my PC amid manual update) and I just finished restoring it.

 

I'm not entirely sure if I used primary or secondary when I attempted this method (about two weeks ago) but I'd try again either way.
I already have nothing to lose since I made a NAND backup of my current state.

And I want to emphasize that I have access to many other Switch units in case I need to salvage files to help me restore mine (from friends and family).

 

I sincerely apologize for the late reply.
I had some recent changes at work and my laptop was away because if it (with all my files and backups).
I got it recently and tested ReTry again with the recently updated Atmosphere but it still didn't work.
I tried again by launching fusee primary manually and I got an other error.
Trying to launch fusee secondary doesn't start whenever I touch to launch it (nothing happens at all).

 

I figured manually rewriting firmware files using PC version of ChoiDujour should fix this ever since I royally screwed myself by updating my SysNAND.
I tried the following guide but somewhy couldn't continue as I got a different result than the file specified in the guide.

https://switch.homebrew.guide/usingcfw/manualchoiupgrade.html

This guide specifies I should use a keys.txt but says I could also use any keys file I have (I have a prod.keys file generated by Lockpick) but it doesn't specify how.
Trying to continue with the guide doesn't generate firmware files as it should nor renaming the file to keys.txt resulted in any changes.
Could anybody please give me any pointers?