This is the problem, never had it before v3.4 firmware update. I am not the only one, there are at least 2 others with the same problem.
https://dashcamtalk.com/forum/threads/cant-access-menu.5236/
Put Mass Storage out of your mind. It is NOT (repeat NOT) connected to a computer, therefore, will never see as mass storage.
There is a combination of buttons to press to enter the Menu.
After it powers on, pressing the Menu button just takes a picture.
Sequence is now:
1. Power On. "Rec" button lights solid. Wait for Viofo splash screen to go away.
2. Press "Rec" button until it starts flashing. Sometimes have to press multiple times.
3. When "Rec" button starts flashing, wait 1-2 sec.
4. Press "Menu" button. Sometimes have to press multiple times..
5. Now it enters Menu.
This is bad programming. Button pushes should take priority. They've tied it to a clock or some other event.
I don't understand why flashing firmware erases all settings. Settings should be in "protected" memory. Every other cpu/micro-controller works this way. I am sure this is another programming error.