1. Flashed with ORIGINAL firmware 2.50, this file nuvi7x5_regionfileonly__250.gcd, added in GarminCure folder, and selected "original" option, and then flashed with this original firmware, flashing finished OK, message "updating sucessfull", press ok, after finishig flashing, on screen of 765 is message "loader loading", and no rebooting.

2. Disconnected device

3. Turned off - forcibly, by pressing turn off button for 7 seconds, until it turned off.

4. Connected device back to PC, and then stupid message "System Software Missing" , and i'm again in same loop, of trying to make visible device in storage mode to PC, that i can then update firmware by webupdater.

Maybe i didn't do something good, pre-BOOT mode, i think can't get, but even that, GarminCure see this item without problem on USB port, and drivers for 765 device are installed, i tried on my laptop Win7 x64, on PC Win XP x86, same problem ...

I don't have anymore idea, maybe to try making .RGN cure firmware from original, by removing 0x66 region, like you suggested for Kenwood where was same problem "loading loader" after flashin all time ?