Defective keypad

I have a new Ring security system purchased through Amazon. Question 1: The USB power connection to the keypad is intermittent. I have made sure the cable is plugged in properly and have tried another USB cable as well. The keypad still loses power on an intermittent basis. I would like to get a replacement keypad and return the defective one. How do I do this? Question 2: I bought too many contact sensors and need to return the excess (seven). I have double hung windows and based on a review, I purchased two sensors for each window when one sensor each works well. How do I do a return?