While currently owning and regularly using two Nuvi’s - a Nuvi 3490LMT and a 1260T – I decided recently to add a 2015 Australia purchased Nuvi 57LMT to the collection, knowing full well the current issues with GMA protection on this model.
I have followed with interest the various threads where Forum members have been able to overcome the Garmin GMA protection on recent Nuvi models and successfully download unlocked maps onto their Nuvi devices
.
My 57LMT has v3.5 firmware as purchased and will not accept an unlocked map via any of the more recent GMA work around techniques that have worked for the Nuvi 55/56/65/66. Rolling the firmware back to v2.4 made no difference to a freshly imported unlocked North America 2016.10 map.
Have any Forum members managed to successfully install an unlocked map on a Nuvi 57? If so, can you share the GMA work around process that is specific to this model?