How to fix "rebooting from reupdate modified .GCD again and again"

The wrong Modified .GCD file can make 3790 to be in rebooting loop.
Rebooting will happen when nuvi boot up and "read" the wrong .GCD file inside .system
The solutions is ..you have to delete .gcd file within .system via mass storage mode.
The problem is you can't acess mass storage mode any more., the solution may be

1). Use modified rgn to flash 3790 in Pre-boot mode. if work--> just delete .gcd file.

2) if rgn file don't work you may try this .... I read from "andynyc2003"

"I was able to delete the problem gcd files from my drive. Here is how I did that,
1. hard turn off the device by pressing the power button.
2. put one finger on the left upper conner, when system came up, press the power button again, wait until the " Turn off the device? Yes/no" show up.
3. plug it in with USB, now computer recognize the drive."

3). or you have to make a cure rgn.