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MM-2 Mastertrol and wiring Sensi Wifi touch thermostat to Zone 2

I have the mm-2 control board on lennox HVAC. i have successfully wired in Sensi thermostat to zone 1 using a relay to separate O/B. works fine. The second zone is the issue. the three wires work the damper for the zone (master Thermostat calls for heat vs cool). i can bring up a C wire, but Sensi thermostat does not power up, indicating that the R wire (T5 on control board) does not carry power. is there a work around here (i have spare wires going to thermostat) to get the new thermostat to work? LOOKING not to have to replace the control board if i don't have to.