Assuming you’re referring to the XR15 From https://www.xfinity.com/support/articles/programming-your-xfinity-remote? If it doesn't have a Setup button (XR15): Turn on your TV. Press and hold the xfinity and Mute buttons together for five seconds until the light at the top changes from red to green. Type the first five-digit code for the TV manufacturer. If the remote light blinks green twice, the code is correct. If the remote light blinks red then green, the code is incorrect. Aim the remote at the TV, and press the Power button. If the TV turns off, turn the TV back on and make sure the Volume and Mute buttons work. If the TV doesn't turn off, try the next code.
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