The messages "No detail maps present" and "Can't unlock maps" are somewhat inconsistent. Looking at your device contents, the only detail map present in the .System folder is "gmapprom.img" with size of 711,524,352 bytes (~679 MiB) and in .System\Map is one of 162,926,592 bytes (~153 MiB) named "D4935310A.img". They are likely to be your UK detail map and the Foursquare i suppose. You should open them in [Only registered and activated users can see links. ] to identify them and check for errors.

The other possibility is that one of the "old" GMA or UNL files from an earlier version map is interfering with reading of the current detail map. You could try removing everything from the Map folder except these:
Code:
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Keep a copy of the GMA & UNL files you remove of course.

You could also try removing all the present detail maps and their associated GMAs and UNLs then replace them on the device in their proper locations with the files you downloaded from GE via the "nuvi clone" SD.