After cure have you loaded the original firmware with Updater.exe?
I suggest you to read with care:
1) [Only registered and activated users can see links. ]
2) [Only registered and activated users can see links. ]
After loading the original fw, create a Garmin folder in sd and restart nuvi and see if a garmindevice.xml has been created, then run Webupdater or Express to load non corrupt files.
Probably in your backup some files are corrupt if nuvis were bricked, so add files one by one, avoid to add old .img .GCD .gpx .gpi .zip .vpm-