New keyfob battery, no lock or start.

I just bought my second Gen 2 Prius yesterday so am fairly familiar with how they work.... This 2006 prius was from a used dealership and is fantastic condition. The salesman had one fob and key and said he just put a new battery in it that morning. He said it was working fine before (and I believe him) but it does not unlock/lock/ or allow the car to be started. When inserted, the car starts fine and the physical key also fits the door lock and works. All of the buttons cause the small red light on the battery to light up so i know it has power.

Ive played around with the button on the steering column and haven't had any success.
I read about programming a new fob via inserting it multiple times, etc. but I dont have the old fob so that won't work.

Any help is greatly appreciated, Thank you in advanced!