(i) Connect it again in preboot to G7ToWin to check the HWID presently displayed by the unit which you've said is 0972 [it would be reported as 'ID: 972' by G7ToWin].

(ii) Look at a backup for your 1490 to find GarminDevice.xml in 'Garmin' folder. Directions are at the base of G7ToWin initial post and at the start of the other thread linked in P#4. It doesn't matter how old the backup is.

Both those HWIDs should be 972/0972. If a GarminDevice.xml shows 1104 to be the unit's original HWID then clearly you've flashed 0972 cure fw to a unit which is physically 1104 hardware and it's now maybe hard-bricked.

So, if you have flashed the WRONG cure firmware, and the unit now shows an incorrect HWID in G7ToWin for its physical hardware i.e. 0972 when it should be 1104, that entirely accounts for the 'System Software Missing' message now displayed when previously it was only stuck on the Garmin Logo screen. To help you clearly we need to know if that has happened or not. We also do need to know how you NAMED the cure RGN file before you flashed it.