Suggest you flash the eMMC and the FIASCO images (in that order). If that's what you did to start with, maybe something went wrong in the process (so you need to try again)?
Flashing just the FIASCO image doesn't reset the whole file system, which is what you need by the sounds of it!

R&D mode is only if you cannot get super-user access, in a normal way (e.g. if "rootsh" is not installed and you can't access the repos) or for actual R & D purposes. Therefore, most people never need R & D mode (IIRC).