You could do the following:
1. run Unflashme.nds and Unflash your DS to its original Firmware.
2. Boot your Flashcard with a NoPass Method (Passme 1,2,3, Superpass ...)
3. Run Flashme once again.
4. Flash your DS until it has reached 3~4 %.
5. Turn it off
6 Congratulatons ! You have Succesfully bricked your DS (and can now only repair it with Parallel Port flashing...)