Thank you very much for your prompt reply.

I was able to load a Cure fw with GarminCure3 following your instructions. It was not easy as I had to try many times until Updater discovered the USB Device and loaded the firmware.

Then I could see the device as a disc unit in the PC. As I could access to all directories and there was not any sympton of corruption, I preferred not to modify anything.

Also, when the device booted with the Cure firmware, Garmin Express detected the device and asked if I wanted to update maps. I went through this process with no problem.

Finally, I created an original firmware with GarminCure3 and uploaded with Updater. It took again a lot of attemps until it was able to get the device detected but finally I could load the original firmare and .... IT WORKED!!!!

So, thank you very much for your valuable help and hope this post can help anybody with a similar problem.