This isn't a buyback case. This is lemon law, and the WA law is clear here (as someone that has actually done a lemon law buyback in WA).
You really need to read this :
General Lemon Law | Washington State
First, the WA Lemon Law doesn't care if you are the first owner or 15th. So you're good there. It covers the car for 30 months, 24k miles.
Second, You don't need a lawyer or anything. But you do need to be active about it, and file a demand with Tesla. You don't wait for them. Your timers start when YOU send a certified letter to Tesla demanding repurchase or replacement. Then you wait 40 days. Then you go to arbitration.
This arbitration is through the WA Attorney General's office and is free. They will hear both sides and decide if this is a valid lemon law claim. Here's the form:
In my experience, Tesla won't want to get to that point, and will offer you a reasonable buyback, but only after the see you are serious enough to file with the arbitration board. You can come up with your own number, but on a car as expensive as an MXP, a good rule of thumb would be $1 per mile up until the defect was first reported. So if the car was $100K + $10K tax, and you drove 10K miles, you'd get $100K back (they specifically owe you the tax back).
The fun part here is that you can easily argue the "reasonable use" mileage stops when you first reported the defect. So you can just keep using the car until they buy it back or replace it for "free" - so them dragging their feet at that point is on them, not you.