Which HWID is your 3770v?
As I know Nuvi 3770v is an Asian device, different HWID (1406) latest firmware here:
Product pages:Code:http://www.iiyonet.jp/software/nuvi3770v_270.zip
What do you have in Update.txt ?Code:http://www.garmin.co.jp/products/ontheroad/nuvi3770v/
http://www.iiyo.net/cProductDetail.aspx?sku=85869