I did this as per your post
"To prevent TT Home from downloading & installing Navcore 9.400
Open the ttgo.bif file with Notepad.
Replace lines 9 & 10 with these:
Save this change by clicking "File" in the upper left corner of windows explorer, then "Save as" ttgo.bak. At this point, there is only a ttgo.bak file in the root, no ttgo.bif.
Disconnect & reboot. Now you will have a ttgo.bak, a ttgo.bif & a ttgo.ori file in the root & no TT Home upgrade to Navcore 9.400."
But when I reboot the ttgo.bak is correct but it creates a ttgo.bif as before I changed it and there is no ttg.ori file? Please can you advise as it keeps trying to get me to download Navcore 9.4 which I do not want.