So I've just gotten the R4i 3DS SDHC 5.0 about a week ago. Turns out my 3DS was already in firmware 6.1.0-12U. If I would have known better, I wouldn't have upgraded it. Cos now I can't use the flashcart. But recently, the developers came out with a new kernel for the flashcart, 1.73b, which is said to work on the latest N3DS 6.2.0-X firmware. I'm not sure what I did wrong, but

I downloaded the new files.
Copied them over.
Selected "Config" on the menu,
then "Upgrade".

Intructions say there would be another "Upgrade" button after that to complete the process, but there's nothing there. Instead, I'm left with a Window with the current supported systems written on it.
"NDSL, NDSi 4.5, 3DS 5.0"
But in the instructions, it was stated there will be a second Window below that stating the new supported systems. Yet, it isn't there.

Someone help me, I'm still unable to use the flashcart with my 3DS. My DSLite however, can.
Thanks in advance!