Hi,

I do not have this device, but as it seems from other posts your device has iGO Primo software on SD card, but only renamed "MobileNavigator".
Couldn't guarantee success, but try to install this
[Only registered and activated users can see links. ]
or this
[Only registered and activated users can see links. ]
or this
[Only registered and activated users can see links. ]
(or any other WinCE version of Primo) on new SD card.

Rename folder Primo to MobileNavigator and inside this folder rename Primo.exe to MobileNavigator.exe.
Before (always) renaming any file in Windows go to Control Panel -> Folder Options -> View and TURN OFF "Hide extensions for known file types" to avoid situations with double file extension like something.exe.exe and to be able to see file extensions at all (do it anyway).

At last, find sys.txt on old SD card and copy it to new one overwriting it (backup old first).

See if it works.
Good luck