Hi @SteveK_7,
I find your situation to be similar to this other user on this forum.
Would you check what the line starting from “L4TLauncher” shows right before the boot splash NVIDIA logo disappears when booting?
L4TLauncher: Attempting Direct Boot
As in
https://www.youtube.com/watch?v=7-U_zGUwAPQ&t=342s
or,
L4TLauncher: Attempting Recovery Boot
If it was showing “Recovery Boot”, we can show you steps to make your unit boot normally from the SD card (or you can follow my comments in the above forum thread).