The Drive series i recall as entering preboot by holding a different spot on the screen. While most automotive devices use the top LH corner, some use the lower LH corner and even some others you need to hold on or over the "G", or on the "RM" in "GARMIN" when it appears. I'd try those 3 alternate methods in that order but have Updater.exe GUI open with the radio button for "USB Device" selected and be ready to click "OK" button, or your PC's Enter key, very quickly when the device's details appear in the GUI. You might only have a very short time of opportunity to start the flash.