What was the form that would indicate if I am eligible for the refund?
Your Receipt FS-6 T indicates if you are eligible to receive a refund.
How do I apply for a full 2-year refund if my registration was never used?
You can apply for a refund of the 2-year registration fee only if the registration was truly never used and it is not more than 60 days from the date the registration was issued.  A processing fee of a dollar is subtracted from the refund amount.  To apply, you must surrender the vehicle plates and the unused registration sticker and stub at the DMV office and request a 2-year refund.  If you are eligible, the DMV will issue a receipt that displays two year refund.