You should know which are the missing or non proper files and have all the updated files specific for nuvi 780 from another user, having the same Nuvi model ,and store them in devices in the proper folders.: complicated
With Webupdater you can properly update your gps ,and you will be able to update it in the future too, in few minutes.
You have to navigate to get to the good.
[Only registered and activated users can see links. ] Password for my files: gpspower.net
Please don't flood my pm box with questions you can post on forum!! You won't hear back from me.
Galaxy S5 Kitkat 4.4.2 / Nuvi1200->1250 / Nuvi3790T->34xx / Nuvi 2200 / Nuvi 66 / Oregon 600