Yes,when on nuvi screen write software missing then nuvi whait in preboot and is ready to flash again but if you turn it off when wrong FW is in nuvi then i dontknow what happend becouse i never try this i always try to flash different FW with no power off.
I search for death nuvi series 1xxx to try repair when he wont boot but i cant find death nuvi 1xxx
Must be some way to repair this nuvi or we must find out how Garmin add FW in chip.