Does the Spark EV have a history of key fob problems? Is it likely that the problem is not with the fob but the car?
No history of fob problems, my two work great, but may need the rubber button assembly replaced at some point.
If you want the issue solved promptly, you should make it very clear to Carvana that they must resolve this problem within the 7 day "test drive" period or they can have the vehicle back.
I bought mine from Carvana in January, and outside of two instances of service vehicle lights, a STRONG
marijuana smell at delivery, a broken door trigger, and undisclosed body imperfections, I've been very pleased.