Hi diane, welcome to MobileRead!
These may not be new ideas but here goes:
1. Have you gone as far as you can with the Update function? You should have Dingo 1.13. If you don't, there's a chance that will help.
2. Older, smaller USB sticks seem to work better for some people.
3. Try, try again. Sadly, it just sometimes takes several (or even many) tries for some unlucky people.
Good luck!! Hope it works soon for you!