Are you referring to the Novatel T2000 here?
You will have to be more descriptive when you say you have exhausted all troubleshooting possibilities. Its important to know what you tried and what kind of error messages you encountered along the way to suggest the next steps accurately.
Please confirm what the specific problem is and the details of what you have tried along with the results from those steps. We can suggest contacting Verizon for a replacement device or not from there.