Check that you have done the procedure well, rar archives are usually overlapping.
NRG extension is Nero image disk file. So, you just have to burn it, using either Nero or [Only registered and activated users can see links. ] (recommended).
But, it is so old device, and maps have also long been outdated. And outdated maps are hardly useful, on the contrary, they can take you where you do not want...
So, I would recommend that you try to find some aftermarket device (based on Android or WinCE) that could easily replace your current one.
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