I'm a little confused by your post, but am assuming that your screendumps are current and you can now browse the Nuvi on your PC.
If so, you can do this:
1. Delete the corrupt POI sub-folder from the Garmin folder.
2. Change the file name '1mapprom.img' to 'gmapprom.img'.
Safely disconnect your Nuvi from the PC and it should now boot normally.