After (apparently) botched map update it hangs at "loading maps".

I used garmin cure3 to generate emergency firmware but I can't flash it - my computer won't recognize the device so updater.exe does nothing.

Tried this: connected the unit via its usb cable, held my finger at upper left corner so it enters pre-boot mode (showing "system" message) and waited for the computer to recognize it as usb device - but that doesn't happen; after a very brief period during which it appears on devices list and drivers start being searched for, the computer rejects it.

Any ideas?