I have read that some people have succeeded in creating a blank text file and renaming it with the .unl extension. I don't know if it has worked for anyone on these units in particular though. However, I think you will be stuck because of the .gma file regardless. As I recall, lollipop's files ended up not working.
However, I re-read the thread and it appears 1 or 2 people posted above that they got it to work without those 2 files by putting the map on an sd card instead of on internal memory.