I am not finding any reports saying that causes a brick, just cause the game to crash. If it did cause an mcu brick, I highly doubt Nintendo would have let that continue to happen.
The only mcu I can find is anyone stupid enough to close their new3DS on 2.1

 

In the European and North American releases of Metroid for the NES, inputting "ENGAGE RIDLEY MOTHER F****R" as the password would cause the game to count 2,755,656 hours of gameplay and overload the system, causing hardware damage to some NES units*. This bug wasn't patched in the Virtual Console version, and would cause a similar error to the 3DS, resulting in bricking crashing**. However Nintendo has since added a patch in the 3DS firmware that would cause Virtual Console itself to crash instead of the entire system.

* I think this was because the NES couldn't handle variables containing a value that high, but not sure. Can someone please check?
** This has now been called into question. While entering the code right now will crash VC and require a power cycle, there are unverified claims that consoles on earlier firmwares can brick.

 

An interesting not, you can say fuck on the Temp. And it only crashed the system, it didn't cause an MCU brick.

 

The video is from 5 years ago but this has been fixed in newer firmwares

 

I heard that invalid LED commands on older firmwares (like 4.x) could brick, but newer firmwares have better error handling. That may be why yellows8 bricked, when using the exact same code, someone else (don't remember the name) had it work perfectly.

 

I already mentioned that one.

no it is. If i recall correctly if you where on a older firmware, it would mcu brick. simmilar on how it's safe to make your led go rainbow colors, but if your on 8.1 or below it would mcu br

here is the really funny bit. Every single letter on that screen is actually converted into code, which means it exists by PURE CHANCE. not set by the programmer

yep your correct. thats why metriod and led, brick. but I'm requesting other knowledge of other bricks. specifically mcu. Any mcu brick as long as it worked at some point.

 

All the reports of the Metroid brick as far back as 2011 say that it was NOT a brick, it just caused the system to crash and be power cycled before it would come back on. Where is the confirmation that is causes an MCU brick? Every report floating around online all confirm a power cycle reversed it. The LED light thing does cause an MCU brick.

I though updating a N3DS on 2.1 caused an MCU brick as well since a hardmod can't fix it.

 

What isn't an MCU brick? No quotes, no context.... And isn't that basically explaining WHY an MCU brick can't be recovered, not saying it doesn't exist? If you need access to the MCU sysmodule to fix it, but can't be turned off without killing the system entirely. Isn't that what we're talking about the fact it can't be fixed? I'm so confused by your post.