I think you are getting a little confused (or maybe I misunderstand what you're saying).... but I'll try & make it a little clearer (I hope)
[Note I've not done a Ak2i update for quite a while, so I'm working from memory]
The [basic] procedure to update a flashcard firmware, is that you....
- Download a firmware update for the flashcard (the AK2i) - I think this is usually a *.nds file (although I think some other cards uses *.dat or some other 3-letter file extension)
- You place the file onto your MicroSD card & put it into the flashcard
- Put the flashcard into your DS
- Switch on your DSlite/Phat/DSi (whatever you have) & select the flashcard from the main DS menu (in a similar way of starting the card to run a ROM or homebrew)
- The flashcard MAY automatically see the update file OR you have to select it to run it like a normal homebrew/ROM etc
- The Software will run & do what it needs to do to update the flashcard firmware
- Usually, when successful, you're told to turn off the DS (it might auto-reboot anyway)
That's it - your flashcard is updated to work on the latest DSi (or 3DS) firmware
Now perhaps you can see (in the forth step)... that IF your DSi is already on 1.4.3, you will
not be able to start/run the flashcard to select the update software, since this particular Nintendo Firmware prevents flashcards from actually running in the first place
So the alternative way to update the flashcard, is to do the above procedure on a DS that WILL allow the flashcard to run as normal.
Since the DSLite/DSPhat don't get Nintendo 'firmware updates' then all flashcards that ran on those systems will still run without any problems, allowing you to select the flashcard update file & run it (The same applies if you had a DSi with 1.4 - this firmware didn't block flashcards either)
NB: just remembered - I think that you have to MAKE SURE you download & run the correct version of firmware update depending on what you were updating the flashcard on (a DSLite/DSPhat or a DSi). I think one had '_DSI' in the title and the other had '_NDS' - not sure though
You shouldn't have any problems since you've said that the card is already updated to run on 1.4.3.
It will only be necessary If/When Nintendo brings out another firmware update that blocks Flashcards again