Steps used to access pre-boot
3. turn off the gps by press power button ~7 sec
4. turn back on, while the garmin logo is showing, put your finger on top of "RM" area, when you should see the word "system" flashing, plug in your USB cable right away, now the updater should recognize the device. But make sure you click OK fast enough, before the "system" went away. I've been trying this whole day, finally figure out.
taken from:
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firmware used:
nuvi37xx_GCDFile__430.cgd
and lastly:
Garmin Cure 3 used to do the flash... Tool was very easy and worked flawlessly!! :)