Hi, I recently bought a used Roamio (TCD840300) with 3 Mini boxes and 4 remotes w/ 3TB and Lifetime. The remotes do not function in RF only IR. I have gone through the remote setup procedure but when I get to the part in the remote setup to "Pair Remote" nothing happens. It states: "Pair Your Remote With Your Tivo Box"...[Not Paired]. When I click on that a message comes up: "To pair a new remote, make sure you are within 3 feet.....Hold the Back and Tivo button together until until the activity light turns solid red... First, none of my large remotes have a "back" button, but the zoom button functions as "back". When I hold those 2 buttons, the activity light does not turn red, no matter how long I hold it. I've tried the Tivo and Red C, Green D, with no results. The activity light never does anything other than flash yellow when I press a command. It seems like none of my remotes go into pair mode. Under Remote diagnostics>Remote Type/Mode>IR Mode. I have 3 of the large remotes and 1 of the small. (see photo) I appreciate any advice. Thanks in advance.