I switched the R4LC board with another known working board and got the same results. The locomotive runs but no couplers, no sounds and the Railsounds board gets hot pretty quickly.
The AC/DC Commander board is marked V5.2 but has a white label partially over it marked AC 7.0,
The radio board is an R4LC C08-S1.
The Railsounds board is 691-RS0E-A00 Rev 4 and the sound set is for the F3.
From the direction of the discussion, I think I need a new AC/DC Commander and, possibly, a new Railsounds board, unless either John or George think it is repairable.
Thanks for your help.