first of all , did you put the right .gcd file for your device? a wrong .gcd file could cause the problem.
After the Garmin Cure did you follow correctly the tips?
Pre-Boot for navigators GPSMAP 62 (s) (c) (t) 78 (s) (c) (t):
1. Turn off the navigator.
2. Hold down arrow "up"
3. Turn navigator holding the arrow "up"
Note: "You can also hold down the" Enter "
give us further information please