Remember when Nintendo warned using piracy devices may disable your 3DS? The latest 3DS system update may well have started that process.
The update arrived yesterday with little fanfare, but here's the official description from Nintendo:
System stability improvements and other adjustments
Further improvements to overall system stability and other minor adjustments have been made to enhance the user experience.
Your Nintendo 3DS system and software are not designed for use with any unauthorized device and/or any unauthorized software. Please note that the Nintendo warranties do not cover any defects to or defects caused by unauthorized devices, software, modifications and/or non-licensed accessories. Furthermore such use may lead to injury to yourself or others and may cause performance issues and/or damage to your Nintendo 3DS system and related services. Nintendo (as well as Nintendo licensees or distributors) is not responsible for any damage or loss caused by the use of such devices, software, modifications or non-licensed accessories.
IMPORTANT: After the Nintendo 3DS system is updated, any existing or future unauthorized technical modification of the hardware or software of your Nintendo 3DS system, or the use of an unauthorized device in connection with your system, may render the system permanently unplayable. Content deriving from the unauthorized modification of the hardware or software of your Nintendo 3DS system may be removed. Failure to accept the update may render games unplayable.
Note that previous updates haven't carried the same message, so it's possible this new update introduces future anti-piracy measures. Of course, Nintendo is known for including a similar message in the documentation for many of its consoles and games, and this could be nothing more than a polite reminder.
We'll contact Nintendo and see what comes back.