Ask about AK2I upgrade issues on the 3DS

Buy a machine when ak2i use ak2ifw_update_3ds_v2_DSL.nds to upgrade, then the machine for the U.S. version of acekard 3ds, Ver. 2.1.0-4U
3DS burn cards can now run, and download the finished game as long as not being able to rename the perfect run (such as the god of the file name)
But there is a problem: As the 3DS version of the machine's firmware version higher than AK2I, later on it can not continue to upgrade in 3DS?
If the firmware with the latest AK2I AK2i update for 3DS2.1 and DSi1.4.3 upgrade in 3DS (Ver. 2.1.0-4U) on which program should be chosen? Whether there will be brick burn card situation?
Thank you

if you want to  buy the ak2i or something about nds you should know this website:gameqo.com

acekard 3ds
acekard card
acekard ii
ak2i
ds one supercard
ds one
ds two
ds two card
ds two supercard
nds r4
ndstt