I am trying to upgrade 3790LMT to 34xx but during the process I was not able to preboot.I tried the left corner and center, some time it will show system, and then loading... then boot normally.
Tried alternate method, entered diagnostic mode by pressing battery icon for 5 seconds and then connect USB cable to computer. In any of the above method my computer was not able to recognize Garmin during the preboot/diagnostic mode.
Have been trying this for hours. Any one could guide me to enter to preboot mode.
Thanks a lot.