if it was factory reset before they sold it to you, you can hold your phone close to the aTV when you power it up, it should pop up something up on the screen if the aTV is in that mode and ready to go.
If your TV supports HDMI-CEC, it should send the basic commands (arrows, enter, and back) over the HDMI cable, enough that you can get what you need working. Once your see the aTV home screen on your TV, try pressing the arrow buttons on the TV remote and see if that changes anything on the aTV.
they also have an IR receiver, if you have an old apple remote laying around (the white or silver version), you can use that.
Or a lot of the "smart" remotes have the apple codes built in, so check the remote for your cable box or TV, you'll probably need the manual for that remote to find the paring code.