if you want play 3ds roms free without damage your console you can choose a sky3ds+ flashcart, it only need copy and paste, and support all the system firmware version include the latest V11.2.0-35:hateit:
why hardmod, its very difficult, and the freeshop you said seems not goes smoothly, many consoles crashed and screen froze when loading to the freeshop, and the download speed is very weird and slow, tried to download a small game, it always can not finish in the end. besides, you said its...
You can try a all new sd card for it, it works on mine, but as my experience, that R4i gold 3ds from r4ids.cn have the best sd card compatibility, Any old sd card can work on it, and steps simple
can not see it clearly, if the card is from r4i-sdhc.com, you can try a new sd card , this may help.
Their sd card compatibility is worse than R4i Gold 3DS card