If by factory remote you're referring to the Cox mini-box remote, you have to program the min-box with a code for the brand TV to which the mini-box is currently connected in order for it to turn the TV on and off and adjust the volume. If the first TV was a different brand than the second TV, you will need to re-program the mini-box with a proper code for the second TV.
Verify the mini-box is properly connected to the TV.
Verify the TV is on channel 3 (using the remote that came with the TV).
Verify the TV input is set to "TV" or "HDMI" (depending on the connection used).