hi guy..more than likely one of two reasons....1) check and double check you are using the correct driving files and 2) you need to clean/service your cartridge slot...also make sure settings are on auto boot on startup. good luck and may the force be with you.
I Impossible unless you give me the product information which in itself is what you need for downloading correct driving files. In a nutshell, find out who the manufacturer of your r4 card is, go to their website and make sure you are using/downloading the correct driver/menu files etc. for you language, firmware etc. And just for good measure, be sure to format your existing micro SD and start fresh which can be very helpful.
If the card is not seen then it should not be the firmware. If the card is seen and there is no firmware then it comes up with Menu? or something to that effect. Put a thin piece of card (or folded paper) between the card and the back of the slot to push the card and contacts together) the most important bit is the bottom 0.5cm of the card as this is where the contacts are. All flashcarts are thinner than a standard cart, this causes the issues.