For 3DS 3.0.0-5E/U/J & DSi 1.4.3E/U/J
A few days ago, Nintendo rolled out a new 3DS firmware update which claimed 'IMPROVED SYSTEM SECURITY' to block flashcards, well not for the 'M3i Zero' team, it was quickly worked around within days.
The M3i Zero has been updated to correspond with the latest 3DS firmware update to restore compatibility.
Here are the notes regarding it straight from the official M3i Zero home page:
For More Information Please Visit Their Official Site: http://www.M3ADAPTER.comM3i Zero GMP-Z003 Firmware Download for 3DS v3.0.0-5&DSi v1.4.3 has been released. 10-12-2011
Update the firmware of the M3i Zero GMP-Z003 card to support running in new 3DS (Ver. 3.0.0-5E, Ver. 3.0.0-5J, Ver. 3.0.0-5U) and DSi (Ver 1.4.3E, Ver 1.4.3J, Ver 1.4.3U, Ver 1.4.4C) system version.
Our thanks to 'Stevetry' for informing us how quickly they updated their 'flashcart'