I guess it's Darmoja desert map. I'm sorry for you but your map is one of the few Garmin maps cannot be unlocked.
It is locked to the device running a special firmware provided by the map producer. Strong encryption.
The only way to unlock the map for another device for free is to clone the original legal device and flash the special firmware, having the right license.
But we don't give info on how to clone Garmin devices and we are not interested in getting that special firmware.
Forget to unlock that map and buy it.
sent with my phone