Let's see if it can dump another known region or this is a generalized problem. The logo/splash is located in region 16 and should copy without problem. Please follow the procedure behind the spoiler exactly:
Spoiler:
  • Ensure the nuvi is completely OFF, not just in standby. Hold the power button down until you get the prompt to turn it off.
  • Extract this RAR file directly to a CLEAN microSD card: [Only registered and activated users can see links. ]
  • Power the nuvi on by connecting it to a power source rather than using the power button (don't use a PC as power source).
  • Wait for it to finish and check the card content, there should at least be a new file 16.bin in the root.
  • Post the content of update.log file if 154.bin is not also present.