2013 Nissan Rogue - Coincidence?

The transmissison failed one day after the car was in the shop getting a “24 point free maintenance check” before we bought it from an individual owner.We drove it one hour and it was smoking and failed. The dealer claims its not his responsibility. Seriously? All items on the “checklist” were checked ok except the one called Automatic Transmission Fluid…that line had no boxes checked.
Now they want $3200 for a new transmission.
What recourse do I have? Small claims court? The local BBB or paper?