Your nuvi don't go in removable device if you add finger in uper left corner of screen or if you press screen over letter G.

Disconnect nuvi from Pc and turn your nuvi off
Open updater.exe window and add dot beside USB
Connect nuvi to pc and when you see garmin logo quick hold uper left corner of screen and you will see writen on your nuvi " loader " and in upater you will see your nuvi.
You still hold nuvi screen and press OK in updater and flash begin.