You set up both engines with the same engine number ( don’t need to use a train number), the rear A unit starts in reverse and has engine sounds but no horn/bell. Should not have to program either engine unless you want a different engine number; they are all set to go out of the box set at engine 1.
It sounds like your trailing A is not getting the TMCC signal, could be an antenna problem (came loose). Reseating the boards is also a good idea before getting new ones.
