I've tried this with my sd cards ,i've formatted then installed new system files but not had any luck
You take a micro sd card (or SDCH) and put firmware on it. (Look for firmware in first link in my signature.) After that you put games in a folder named NDS. Then you can put any emulators or homebrew you want in the root of the card. If you have put firmware on the microsd but still get the loading screen likely it is the wrong firmware, as there are many variations. Try them all if you have too. Since you have R4 SDHC make sure you look for firmware for that particular R4, because there are MANY R4 Cards. Hope this helps!