It's expected not to go past the logo on reboot with cure fw on board because that's part of the function of the cure as it cannot and so it's not intended that the unit boot further. That's normal. Then not being recognised by the PC isn't.

The unit attempting to reboot itself with cure fw certainly isn't normal either, it should simply stick on the logo. Your 1390 has exactly the same symptoms as the 1490 in the thread i linked. Please read that thread fully if you haven't already and try all the suggestions there. Did you try the fix from Post #20 in the other fw cure thread? i.e. this:
Quote Originally Posted by VMatas View Post
Problem solved without Garmin costly help

Steps:

1. Load cure firmware as usual
2. switch on Nuvi, and tap left top corner, but after 0.5 - 1 secs later, than for pre-boot mode
3. wait for "Loading maps", then wait 5-7 secs and press power button
4. wait for copyright sign (C) and release power button
5. wait for language selector and release top left corner
6. IMMEDIATELY and very fast tap few times Ok button
7. Enjoy Nuvi
8. connect to PC, erase bad files and restart.

Many thanks to RTuERkaM from gps-forum Russia for its support and persistence.

P.S. You must experimentally select time in step 3. If selected time will be to short you don't see (C) - Nuvi will be switched Off.