Than do it the fast way
Download the current 910.4892 AU map, the 9.510 Navcore .cab file from the Navcore section and FastActivate.
This completes the current versions you need for a complete update.
Unpack the Navcore to a SD card or USB stick,
add the downloaded map, make sure to unpack the map FILES! into a folder - you don't want the map files in another sub folder,
unpack FastActivate into the root and you are ready.
Once you have the device to play with:
Make a full backup using Windows Explorer,
Delete all from the device except:
ttgo.bif
the folders "voices", "LoquendoTTS"
and personal stuff like MP3's or videos if existing
Now copy the content of your prepared USB stick to the TT and when done start FastActivate (the one located on the TT) to patch Navcore and map.
In case the old bloke still needs his favorites copy the file "mapsettings.cfg" from the old map folder (backup!
) into the new map folder on the TT.