I had the same problem. You have to get the firm.7z file from the github and choose rei-n3ds drop the firmware.bin into the aurei folder. The reason, I think, that the light flashes and goes off is because you probably dropped the fimware90.bin into the aurei folder.I've downloaded the latest version of AuReiNAND (3.13 released 10 mins ago) and extracted all files from the 7z archive (AuReiNand.dat & arm9loaderhax.bin to the root and the 3ds, aurei and menuhax folders were merged).
Still the same result, no boot?!?