I tried plugging the GPS into 3 different PCs, with Windows 8.1, 7 and XP, using 3 different USB cables, including a brand new official Garmin cable out of desperation.
I was always able to get both the device drive and MicroSD card inside of it recognized as drives in Windows Explorer, but the Garmin Express would never open up as it was supposed to, the moment we plugged the device in, nor would it ever find the device when we opened it manually.
We tried everything, including older Garmin Map Updaters and the MyGarmin interface on their site.
It wasn't until I wrote their customer service for help (Being they don't deign to offer after hours phone support).
I was shocked to get an email back a few hours later and DAD GUM if they didn't actually give me workable advice, so since it worked for us, here it be for you.
Personally, I think you can get it to work just by removing that GarminDevice xml file in the Garmin folder. I'd try that first.
I also first backed up all the files I removed from the device folders. It was about 1.7GB.
When the device is connected to the computer what do you see on the screen of your device? If the device displays the Garmin logo with a picture of the device connected to the computer tower, you should be able to go into the nuvi drive and remove unnecessary files from the device. I have included these steps below.
1. Connect your GPS to the computer and allow the computer time to find the device
2. Open the Garmin drive, (PC: under "Computer" or "My Computer" Mac: On the Garmin Drive mounted on the desktop)
3. Inside the Garmin drive you will find several folders, you will want to go into each and remove any files you will not be using.
Help - Remove any language that you will not be using - You will want to keep American_English file
Keyboards - Remove any keyboards other then keyboards you will be using as well as the EN_US file
Text - Remove any text files that you will not be using, please keep any that begin with EN_GB
Voice - Remove any voice files that you will not be using, please keep any American English Voices
Garmin - inside of the Garmin Folder, delete the GarminDevice or GarminDevice.XML Folder
4. Once the files have been removed, disconnect the GPS from the computer and allow it to power on.
5. When the device is loaded to the main 'Where To/View Map" screen allow it to wait there for appx. 30 seconds
6. After 30 seconds, reconnect the unit to the computer and Garmin Express should find the device.
If your device is not displaying the Garmin logo with the picture of the device connected to the computer tower, please connect the device to a different USB port on the computer. If you are using a desktop, please connect the device to the USB port on the back of the computer. If the device is still not connecting to the computer please check the cable to make sure it is the Garmin branded cable. If you look at the end that connects to the computer, below the USB plug the Garmin logo should be embossed on the casing below. If you do not see the Garmin logo on this cable, please try to use a different USB cable. Although these cables look similar and fit they can often transfer data differently.
If you are still having trouble with your device connecting to the computer, please follow the steps below to perform a soft reset.
1. Connect the device to the computer or vehicle power cable
2. Press and hold on the power button for 10-15 seconds
3. Release the power button and the device should power back on.