Then, you need direct access to internal memory (IF it is possible).
The principle is always the same (the next story is general, and there is great IF before every step):
[AND BEFORE ANY ACTION DO THE BACKUP, ALWAYS]
you see the name of the folder where the navigation software is located (fore example NAVIGATOR, GINY, ...etc)
you see the name of the main exe file (navi.exe, or giny.exe, or...whoknows)
Give your iGO folder same name as original in device
Give iGO.exe same name as original in device
Delete original navi folder from device
Put renamed iGO in device
Try

Of course, this is a rather simplified procedure.
You must first compare the structure of the software in the device, to see if the matches the one with iGO.
Even after all it can happen that it does not work. Then you should revert backup.
Well, again, maybe this is not worth the effort. Tt can be much easier to sell it to a some Korean and buy any cheap modern device that has a bunch of net.