I did a lemon law buyback a bunch of years ago with my 2004 Armada. I also live in California. I used an attorney, rather than try to do it myself. They reviewed my case for free, and then let me know if they felt I had a case (the answer was yes). They told me they would submit a letter to Nissan demanding a buyback (actually, they requested 3 times the value of the car; always ask high, settle low!!). The fee to do this was $750, only payable if a buyback occurred. About a month later, I got word back from the attorney that Nissan had agreed to buy my vehicle back at full purchase price, minus a mileage allowance from the mileage on the car at the first occurence requiring a dealer visit (in my case, was 1700 miles), plus registration fees, taxes, and the costs of any modifications I had done to the car (tint, etc). I have no idea if Nissan also paid them a fee. I was instructed to take my car to the local Nissan dealer for inspection, kind of like a lease return. They inspected the car (pretty perfunctory), and then handed me some paperwork, and I left the car with them. About two weeks later, FedEx showed up at my door with a check for the full amount, minus the $750 for the attorney. Easy-peasy. Everything on-line or on the phone, no face to face interaction. For $750, I got a professional letter written on the letterhead of a law firm known for Lemon Law cases, and somebody to handle all of the logistics for me.
I took the money and went out and bought a 2006 Armada. Just recently got rid of my 3rd Armada, a 2012.
Keith