Normally the mapsettings.cfg can be found on the SD card, but if you use internal and external simultaneously, which is not possible with all TomTom's, it could also be in the internal.

You could test with a random empty SD card formatted FAT32, place it in the device, hard reset and start and see if a mapsettings.cfg is being written.
That will probably not be the case and then put a navcore on it, for example 9.510 and do the same trick again.

Now definitely a mapsettings.cfg should be written and you should end with the error message no map found.

Depending on the Bootloader, make sure you use a SD card up to a maximum of 2GB for certainty