Thanks for your kindly advice.
After trying many ways, now after entering in pre-boot mode, Garmin updater could detect Nuvi USB device and ready to flash.
But my present problem is Nuvi repeatedly reboot after connected to PC.
So, after Updater detect USB and I click "OK" button to start flashing, the flashing screen appear and process start initializing, the Nuvi immediately reboot. Then the updater error out as Nuvi no responding and stop flashing.
I have tried more than 20 times but it's always reboot at flashing initializing stage.
Please kindly advice me for further steps or solution.

Thanks in advance,

JUR