The only good news from G7ToWin is that HWID is still 1113. It shows the last fw version successfully loaded was V3.00. It's a big jump to go from V3.00 to V7.30 but that's not causing the problem.

The bad news is that the device's 10 digit UID has been lost, indicated by it now showing as "Unit ID: 0". That's another strong indication of physical flash damage. There's still a slight chance it has very severe data corruption which involves multiple regions. Clearly at a minimum, regions 14 and 41 are known to be affected. They contain the main fw and nv memory respectively, both essential for proper working.

If it can't be recovered from SD it's a certain write-off. Try the following please, it uses a modified ramloader which bypasses involving the fw in rgn14 so can sometimes start corrupted devices which might otherwise be unresponsive to an SD's presence. It will attempt to dump a copy of its nv region:
Spoiler: Click for Files
[Only registered and activated users can see links. ]
[Only registered and activated users can see links. ]

  • Extract "SD.zip" to a clean SD
  • Insert the card in the 78
  • Extract "RGN.zip" anywhere convenient on your PC, drag 111301000730.rgn onto Updater.exe and select the USB radio button
  • Connect and power on the 78, watch Updater's GUI
  • When the device's details appear in the window next to "USB Device", press "OK"
    [Only registered and activated users can see links. ]
  • If this works, "Loader" or similar should appear on the 78's screen within a few seconds. Wait for the flash to finish indicated by another reboot attempt to the "System Software Missing" screen.

If it doesn't do anything there's nothing else to try. If it does read the card, please post a link to the 2 new files generated on it, "41.bin" in Garmin folder and "Update.log" the 1113 folder. The LOG file can be read by any common text reader, the BIN file will show as it is with FFs only in a hex reader. It's encrypted but i can decrypt it to see what's really in it.