This involves a semi-bricked Nuvi 1350 (US/ North America I believe). It's old, but worked up to about a week ago. It froze while being used in a car and since then it stays stuck on the logo and keeps going off and on without booting or properly getting into pre-boot mode by plugging in the USB cable. I have tried both GarminCure3 and QuickCure3. Here are some details:

1. My 8GB flashdrive has been FAT32 reformatted as a properly as a FDD bootable device using latest version of RMPrepUSB.
2. The PC does not recognize it, unless I press upper left screen and plugging in USB cord.
3. I was able to get ID information using G7towin64: software version 6.30, HWID 0972, Unit ID 3827336719
4. Garmin Express does not recognize unit regardless of whether upper left is pressed before making USB connection.
5. Webupdater sees unit, but when attempting to reinstall, it says file is corrupt.
6. I have used GarminCure to make 2 firmware files (one cure and one original), but I am unable to install either one.
7. I am able to flash the Quickcure3 firmware (after renaming it to 097201000630), but I am not able to do anything more.
8. I am not 100% certain that I have the correct gcd file for this unit. I found links on this and another forum for nuvi13xxseries_GCDFile_630 and nuvi13xxseries_GCDFile-MTK_630. I believe that my 9720 does not use an MTK file. Garmin seems to have taken all firmware files off of its website. If I had an older version, I might have tried that as well.
9. I have tried renaming my GCD file to gupdate.gcd and putting it into both the root directory and a Garmin subdirectory of the flash drive.
10. I have tried to follow both the instructions at the start of this thread as well as the "How to unbrick a nuvi" doc file, but still no luck.
11. Maybe I am doing something obviously wrong.

Any advice would be appreciated. (Not sure this old unit is worth the effort, but I did like it.)