Why did you change the TCM? I ask for two reasons: 1) I have never heard of anyone needing to do that, ever. 2) Your problem appeared coincident with doing that.

Ultimately you will probably need someone to help you who knows more than me. I do know that there is a starter lockout contact/switch inside the transmission that acts basically like the old neutral safety switch, except it is inside the transmission. If that signal is not being received by the TCM for what ever reason the it will lockout the starter. You may need to get a mechanic with a dealer-level scan tool to sort out what is happening. Maybe someone else has an idea.

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra