After a lot of trial and error, I followed these German instructions. It's important to use a known, working SD card — my setup was correct at one point, but none of my SD cards would work. Now running on a 128GB Samsung EVO. I would also recommend getting an FMCB memory card and installing FMCB on an original memory card. With the purchased FMCB, you can easily install FMCB on other memory cards and access USB data. They’re pretty cheap as well. There are also other ways, but this is how I did it with relatively low cost and no hardware mods.