You need BIOS for the PCSX ReARMed core:
sdmc:/retroarch/cores/system/
scph5500.bin
scph5501.bin
scph5502.bin
PS1 emulation on the 3DS is hit or miss. Anyway, I'll leave the rest up to you to figure out if nothing else is wrong with your setup.
I still recommend you scan the emptied out SD card with H2testw if this has never been done before as precautionary safety for your data. People often times do not place enough importance in making sure their cards are 100% proven legit and are argumentative about checking. Why anyone wants to gamble their precious saves and memories has only themselves to blame when their files end up corrupt or missing.