Today DSTTi update patch for DSi V1.43 and 3DS V2.1.0-4 has released, now you can use it to update your DSTTi flashcard and then make it work on your DSi or 3DS latest firmware. Good news for DSTTi users.
Download here: DSTTi update patch for DSi V1.43 and 3DS V2.1.0-4
Notice: the link above includes the firmware and update, you dont need to download other files.
More info is here: DSTTi
DSTTi Update guide
1. Download the files via the abve link
2. Extract the zip file and then put the "DSTTi Firmware Update for DSi Ver1.43+3DS Ver2.1.0-4" fold in your SD card
3. Put the SD card and DSTTi in your DS console
4. Power on and run the update file
5. Finish the update
6. Take out your DSTTi and then put it in your 3DS V2.1.0-4 or DSi V1.43
Have tested it on my DSi and 3SD , working great, feel free to update your DSTti, guys.