Review Sthetix fusecheck: how did this tool get released?

[auggiethecat]

For a tool exclusively about downgrade eFuses, you would expect the author to know how they work, right? Right?!
Well, the readme pretty unambiguously says this: (note: this is also present in the functionality of the payload)

Why Do Fuses Matter?​

Nintendo uses a hardware anti-downgrade mechanism called "fuse burning." Each major firmware update burns additional fuses, and the console checks this count during boot:

• Too few fuses burnt = Console will black screen on OFW boot
• Correct fuse count = OFW will boot normally
• Extra fuses burnt = Console will black screen on OFW boot

Yeah, this is incorrect. Here is a crash course on exactly how downgrade fuses work:

The downgrade eFuses are burned and checked only by the official bootloader. They are to "prevent" you from downgrading your firmware.

• (↓) If there are less burnt eFuses than expected, it will burn more the ones that it expects.
• (=) If there are exactly as many burnt eFuses as expected, it will just boot.
• (↑) If there are more burnt eFuses than expected, it won't boot (blackscreen).

For example, if you boot 21.0.0 (which expects 22 burnt eFuses), but you only have 4 burnt eFuses, it would burn 18 fuses. https://switchbrew.org/wiki/Fuses#Anti-downgrade
(read this page for other uses of eFuses and a more technical explanation for how exactly the bootloader handles downgrade fuses)

If sthetix is right, and this is how fuses work, updating to major versions* wouldn't work at all. The official bootloader is the only thing that touches fuses. When you update, it reboots. The firmware is installed at that point, so when booting it would expect the new burnt eFuse counts. Since the actual number is lower than that, it burns the eFuses, then continues booting.

And, You can test this! Check you burnt eFuse counts (hekate or this payload), then update in syscfw (via Nintendos servers to rule out the official updater as the thing that burns fuses), then check burnt eFuse counts in hekate, then boot ofw (see that it works) and check eFuse counts again.

This tool is not only mildly pointless (since its a feature of hekate anyway, (console info -> hw & fuses)), its also completely wrong. By being this wrong coming from a place of trust, it spread misinformation and wastes people who help's time and energy.

If you have time and care, contact sthetix about this, or open an issue (or pull request if you know how to!) and tell sthetix about this. I would not recommend using this tool until its fixed, as in its current state its just wrong.

*downgrade fuses aren't burned every major version, but closer to a "whenever nintendo feels like it". Its pretty close though. See the table here: https://switchbrew.org/wiki/Fuses#Anti-downgrade

 

[masagrator]

Jeez, you wrote this like someone was killed or something. It's not like sthetix is some major player on this scene that making any blunder is a stain on their reputation. And this mistake is not harmful, just will waste hours for some few random people seeking help with black screen.

Issue report already exists, just wait patiently for answer.

https://github.com/sthetix/FuseCheck/issues/1

This can take days. For many people Holidays just ended.

 

[Thorhax]

Don't you dare talk smack about Sthetix.

 

[auggiethecat]

Don't you dare talk smack about Sthetix.

I did next to zero smack talking.

Post automatically merged: Jan 5, 2026

Jeez, you wrote this like someone was killed or something. It's not like sthetix is some major player on this scene that making any blunder is a stain on their reputation. And this mistake is not harmful, just will waste hours for some few random people seeking help with black screen.

Issue report already exists, just wait patiently for answer.

https://github.com/sthetix/FuseCheck/issues/1

This can take days. For many people Holidays just ended.

I might minorly disagree on the finer details, but either way, criticisms duly noted.

 

[ikynx]

It's not like sthetix is some major player on this scene

I would respectfully disagree. He's one of the most major packagers out there (should/shouldn't use packages is not the point), his tutorial videos are really good, and he's a damn good pro modder (and happens to be a great person too). Of course he's not on the scene level of atmosphere/hetake team, but he's a reliable member of it.

 

[thesjaakspoiler]

I think you overlooked the feature of CFW where they skip the part of the bootloader that checks and updates the eFuses.
So you can update your CFW all you want but the eFuses never get updated.
Only when you update the OFW and reboot once more in OFW, the fuses will be burnt.

That part of the bootloader of the OFW that deals with eFuses runs after Hekate so if you don't go into the OFW and reboot once more, you will see the old fuse information.

 

[SuffahBish]

I think you overlooked the feature of CFW where they skip the part of the bootloader that checks and updates the eFuses.
So you can update your CFW all you want but the eFuses never get updated.
Only when you update the OFW and reboot once more in OFW, the fuses will be burnt.

That part of the bootloader of the OFW that deals with eFuses runs after Hekate so if you don't go into the OFW and reboot once more, you will see the old fuse information.

Yeah. And this tool will show you blatantly wrong BS like this. How do you guys think this is OK? Lmao.

(Not my pic.)

 

[Hayato213]

Yeah. And this tool will show you blatantly wrong BS like this. How do you guys think this is OK? Lmao.
View attachment 549775
(Not my pic.)

Well the info is correct, the expected fuse count is 22, while the burnt one is 20, so if on firmware 21.1.0 boot into ofw, fuse get burnt. You can be on higher firmware and lower fuse count if used correctly with autoRCM.

 

[SuffahBish]

Well the info is correct, the expected fuse count is 22, while the burnt one is 20, so if on firmware 21.1.0 boot into ofw, fuse get burnt. You can be on higher firmware and lower fuse count if used correctly with autoRCM.

It clearly says "Missing 2 fuses. OFW will not boot. System will black screen on OFW boot." Which is wrong. Blatantly. Plain and simple. If you boot OFW it'll simply burn those fuses. It also has "STATUS: CRITICAL ERROR" there like something is wrong with your console. There isn't. He just doesn't know how the fuses work. Stop defending this crap.

 

[Hayato213]

It clearly says "Missing 2 fuses. OFW will not boot. System will black screen on OFW boot." Which is wrong. Blatantly. Plain and simple. If you boot OFW it'll simply burn those fuses. It also has "STATUS: CRITICAL ERROR" there like something is wrong with your console. There isn't. He just doesn't know how the fuses work. Stop defending this crap.

I do agree with you that that is an error, if you read what I wrote I did said fuse get burnt.

 

[SuffahBish]

I do agree with you that that is an error, if you read what I wrote I did said fuse get burnt.

You also said the info is correct when it clearly isn't.

 

[auggiethecat]

I think you overlooked the feature of CFW where they skip the part of the bootloader that checks and updates the eFuses.
So you can update your CFW all you want but the eFuses never get updated.
Only when you update the OFW and reboot once more in OFW, the fuses will be burnt.

That part of the bootloader of the OFW that deals with eFuses runs after Hekate so if you don't go into the OFW and reboot once more, you will see the old fuse information.

That is not something I was aware of. Interesting. Apparently through some kind of magic (to me at least) hekate manages to use Nintendos bootloader while bypassing fuse burning. https://github.com/CTCaer/hekate/bl...b78a29aff130cc90f35/bootloader/hos/hos.c#L746

 

[auggiethecat]

Sigh. (https://github.com/sthetix/FuseCheck/issues/1#issuecomment-3736446205)
He dismissed everything using information that's half wrong, and half anecdotal evidence (incorrectly installed modchips or something, as they can and should boot ofw like that).
Then he closed the issue, locked it to contributors and marked it with the "junk" tag, which is described as, "useless conversation based on subjective and personal issue"
I'm making a corrective fork, but I don't expect them to merge my pr. If anyone else cares to try, please do. Keep me posted.

 

[SuffahBish]

Sigh. (https://github.com/sthetix/FuseCheck/issues/1#issuecomment-3736446205)
He dismissed everything using information that's half wrong, and half anecdotal evidence (incorrectly installed modchips or something, as they can and should boot ofw like that).
Then he closed the issue, locked it to contributors and marked it with the "junk" tag, which is described as, "useless conversation based on subjective and personal issue"
I'm making a corrective fork, but I don't expect them to merge my pr. If anyone else cares to try, please do. Keep me posted.

Personally I don't think this tool even needs to exist. Hekate already shows your fuse count. But that thread is peak r/iamverysmart material.

 

[auggiethecat]

Hekate does show this info, but it can be, complicated/unintuitive for people who aren't knowledgeable. I do think they should learn what stuff means instead of something like this, but the tool isn't the problem for me in this case. Also this is consistent with what I have seen before. I don't know what it takes for sthetix to change something like this. All I know is what is doesn't.

 

[SaudiCraft]

I think you overlooked the feature of CFW where they skip the part of the bootloader that checks and updates the eFuses.
So you can update your CFW all you want but the eFuses never get updated.
Only when you update the OFW and reboot once more in OFW, the fuses will be burnt.

That part of the bootloader of the OFW that deals with eFuses runs after Hekate so if you don't go into the OFW and reboot once more, you will see the old fuse information.

If you update the firmware via daybreak I'm pretty certain you cannot enter OFW to burn the fuses. Go try it and come back to me.

 

[SuffahBish]

If you update the firmware via daybreak I'm pretty certain you cannot enter OFW to burn the fuses. Go try it and come back to me.

Hold + & - volume while you boot. It'll bypass the modchip and boot directly into OFW.

 

[namename11]

Shittix is a known tard in this scene, ignore and carry on.

 

[SaudiCraft]

Hold + & - volume while you boot. It'll bypass the modchip and boot directly into OFW.

I'm sorry but you don't have the slightest clue. When you update in that manner you get semi-bricked. The only way you're going to enter OFW again is if you initiate a system update from the official update menu.

sthetix is a good guy and I can attest to his efforts because he helped tens of thousands unlike you people who think it's cool to dunk on someone. You people are simply dicks.

 

[The Real Jdbye]

That is not something I was aware of. Interesting. Apparently through some kind of magic (to me at least) hekate manages to use Nintendos bootloader while bypassing fuse burning. https://github.com/CTCaer/hekate/bl...b78a29aff130cc90f35/bootloader/hos/hos.c#L746

It's effectively CFW, there is no way to boot fully stock OFW from Hekate.