Sorry, but it's simply not possible. Even on a hardware revision less than J, no one has bothered to figure out how to get a version of CAS higher than 3.1 or 3.2 running. There are plenty alternatives, such as KhiCAS, however.

EDIT: It is now possible to boot CAS firmware on non-CAS hardware via nBoot+ControlX.

So just out of interest: Who's still around here and freaking hyped for a possible new update?! No one? Huh... well then who's still around here anyways?

I know I'm a tad late, but I personally would be very hyped.
I've been playing Crafti a lot, and while that's cool and all (with 3D and stuff), it doesn't have survival, which makes it quite boring (building at 10fps is still pretty fun though ). Meanwhile, this does have survival! I've never actually used this, except maybe once, but then I stopped using it, for whatever reason. But what's planned for this seems really exciting.
I doubt that no one wants a new update... You already have two people excited, and I'm sure there are many more people who don't have an account that want an update, too.
By the way, I would suggest reposting this on a different site, like Codewalr.us; it's a lot more active there. Omnimaga is practically dead.

Yes, I'm here again. The flow of calculator shows no sign of stopping... until now?
One day, I was messing around in MicroPython on my P-0211A TI-Nspire CX, and decided to input a math expression that has a very large answer, which I knew would freeze the calculator. The calculator froze, as expected, so I rebooted it via the button on the back. It loaded the OS, it went to the clock screen, and...
Nothing. The clock was simply frozen. I waited for minutes, and absolutely nothing changed. I tried reloading 4.2.0 without the boot2 (TNOCed) as to not lose nLaunchy, to no avail. I tried reloading an unmodified 4.2.0 OS (with the boot2), to no avail. I tried formatting the entire system and reloading the unmodified 4.2.0 OS... to no avail. The only thing left I could think of doing would be reflashing the entire OS at RS232 level, but I don't have an RS232 device, and I'd rather not go that route just yet. I already have my documents safe, so any suggestions would be greatly appreciated. Thank you!

By the way, I do have a computer called a "PocketCHIP", it's similar to the Raspberry Pi, would that work as an RS232 device? It has GPIO pin slots, if that helps.

Well, AFAICT you still can find the GBA emulator gpSP-Nspire source code here:
https://www.omnimaga.org/ti-nspire-projects/gpsp-nspire-(gba-emulator)/msg314055/#msg314055

Have fun 

Oh, that's swell! Hopefully someone will update the code and fix it for the new screens. That someone won't be me, that's for sure; I've got no idea how to write code (other than very basic Python). I'm planning on learning though

Hey guys!
Ive tried downgrading 4.2 pn my ti nspire cx using your tutorial.My first question is where do I have to enter my hardware revision in nsnandmrg?I have the hw revision Y and I am curious if this is even working for me (is it???). I have tried it without entering my hw revision because I dont know where so I set my min os to 0.0 and tried to install 3.9.1.The problem is when it boots and has finished loading half of the screen goes black and I cant do anything.Then Ive tried the same installing 4.0.3 which worked and I could get into the menu and it also said my version was 4.03. But the problem on this version is that my device reboots everytime I press ctr plus w to install ndless(and I used the right ndless version file).So on this version I cant even install ndless... Is there any option I can get this to work???Because gba emulators run rally slow in compatibility mode and I need to get it on the last version supported to run faster (4.0).Is there any way?

Only hardware revisions equal to or less than V can downgrade to anything lower than 4.3. Your calculator, a revision Y, is stuck on 4.2 in compatibility mode forever. This is unlikely to change, as the hardware itself updated and can not be changed via a software downgrade. Your best option is to sell your calculator and buy an older one from Ebay or something, preferably a revision I or less if you want nLaunchy or nBoot+ControlX or revision V or less if you only want nBoot+ControlX.

Now that nBoot is here, and I have the ability to replace my apparently defective Nspire for potentially any hardware revision, I'd like to know what to pick if given a choice.

Huh? nBoot let's you do that? Or are you just saying that you now have the ability to buy a new calculator?
Anyway, if you mean you could buy a new calculator, I would go with the revision A; it's before TI started changing all the parts for cheap garbage, and nLaunchy supports it. If you want the latest parts possible, you could go with the revision I; it's the last calculator before they disabled booting the 3.1.0 boot2, somehow. If you don't care about nLaunchy, you can use the revision V, which was the last revision before they changed the screen and made most ndless applications incompatible.
If you mean that nBoot let's you do that, then all the things I said about hardware (the screen, the parts) don't matter. I'm not sure what changing the revision via software would really do for you, most revisions are hardware-related (except for the boot1 updates, but that's read-only [without heavy modification]).

Is ndless.cfg.tns in the right location? It should be in /documents/ndless/ndless.cfg.tns

Yes, it's definitely in the right location, sitting with ndless_resources.tns and nover.cfg.tns, and various other files.
I edited my above post to include my file structure, in case you wanted to test it.

EDIT: Wait, could my ndless-transfer folder be the issue? Seeing as it also has an ndless.cfg.tns. I was using the folder to transfer ndless to other Nspires someone wants "hacked", but I've never actually seen anyone else with one (except some person I don't know), so it wouldn't be too bad if I had to delete it.

EDIT2: Haha, wow, after all that, it was the ndless-transfer folder! 
I deleted it, and everything works now. I'm very gracious that you stayed with me through this adventure!

I'm assuming you have hardware revision I or earlier. In that case, you can use nsNandMgr to flash boot2 3.1. Do not attempt this if you have hardware revision J or later!

Okay, I flashed a boot2.img from TI-Planet using nsNandMgr, and by some miraculous force my calculator didn't brick... Except, after I rebooted my calculator, both the "About" button and nsNandMgr report my boot2 to be 3.2.4!? I'm so confused...
Also, I have a revision A calculator, and I would really like to not brick it (past the redemption of the fabled RS232), not only because it supports nLaunchy, but because it's easier to hold (heavier) and the screen isn't as blue as the newer ones.