The complete solution - user reset is NOT necessary:
Whenever I purchase a new electronic device, the first thing I do is update the firmware. This has me in a bind in this case.
I updated my Nuvi firmware, then my BT firmware.
A few days later, I got the "Enabling Bluetooth" hang. I followed the advice on this page, but "Bluetooth Firmware Update" would not appear in the webupdate list.
1. Browse here and install the latest version of WebUpdater:
2. Turn on your Nuvi, press view map, press speed, press and hold the middle of the speedometer (the circle that says 0.0mph in it). After five seconds (maybe a bit longer), the engineering menu will appear.
3. Press "Next" five times (once for each page). You will arrive at the "Bluetooth Status" page.
4. Press "Clear". Confirm by pressing "yes".
5. Press "Updt PR". Confirm by pressing "yes".
6. This probably did _nothing_ for you, but to be thorough, I've included the steps.
7. Connect the Nuvi to your computer. Run the webupdater and if the latest version is already detected on your Nuvi, simply proceed and browse the list of further updates.
8. If "Bluetooth Firmware Update..." (or similar text) DOES NOT APPEAR skip to step 10 below, otherwise complete your fix with the next step, step 9.
9. If the "Bluetooth Firmware Update..." (or similar text) appears in your list, select this update and agree to term of service, and have the updater load the firmware onto your device. Unplug your device. It should powerup automatically. Power off. Power back on. Your BT should be back in business. Do NOT continue with the next steps. You are done.
10. If "Bluetooth Firmware Update..." (or similar text) DOES NOT APPEAR in the list, then you need to remove the offending update that is making WebUpdater believe that your Nuvi is up-to-date.
11. You can access the Nuvi by clicking on "My Computer" and double clicking the Nuvi link.
12. Click the "Garmin" folder.
13. Click the "RemoteSW" folder.
14. DELETE "006B055301.GCD". This file will be one of two GCD files in the directory: <DRIVE>:\Garmin\RemoteSW. The file without the "Date Modified" is the original firmware. The other file is the new firmware that the Nuvi believes is installed. By deleting the newer of the two files, WebUpdater will see that your Nuvi is out-of-date. Return to step 8 to continue your fix.
This should resolve all permutations of this nasty bug.