These things are better fixed on the bench of someone who knows the boards. If it will run in conventional and not TMCC, start with a continuity test between the antenna and pin 23 on the R2LC board. Follow the grey antenna wire to the white Leoco connection on the motherboard. Pull it off the motherboard and plug it back in. I would then pull all three boards and replug them back in. Next I would do a reset and reprogram the locomotive with the AUX number in your manual. These things are simple and the fact you are running in conventional is a help.
A few questions. When you run in conventional, are all the sounds, smoke and control working properly? When you power up in TMCC mode, what happens? If you have no smoke in conventional, pull the 3 pin plug off the end of your smoke unit and try to address the engine again in TMCC. Do you have another R2LC you can swap out to check things?
One last thing, check the run/program switch for continuity in each direction. I have seen these that are bad. Let us know how you make out.
