Hi, I had the same problem, too. Maybe you solved it meanwhile, as you posted nearly a year ago. Here is how it worked for me: After recalbox has booted, press F4 to end it. You see a black screen. Now press ALT+F2. You are now prompted for login. Login using user "root" and password "recalboxroot". Go to the root directory using "cd .." until you are there. Now go to the specific recalbox roms directory using "cd recalbox/share/roms/psx". Put your rom files on a usb stick formatted with FAT32, and plug it into your raspberry pi. Now you can copy the files using "cp ../../../../media/usb0/. ." Wait until the files are copied, then you will be prompted again. Unplug the usb stick and restart the box using CTRL-ALT-DEL.
