Hello. I also have the DNX692 but have been unable to get my map to read from SD. I have the 2017.20 that I pulled from my NUVI with lifetime map updates. I finally got it to stop saying map file was corrupted but still get the maps are unlockable error even though they are unlocked according to Basecamp. Could you show my what your SD card looked like? What UNL files, etc? How about steps you took? Thanks!