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Nest Learning TStat (3rd) won't recognize wires

Community Member

I received two 3rd generation learning thermostats for Christmas. I have one HVAC system, with TStats for upstairs and downstairs. They run through a Honeywell HZ311 control board.  I installed the first unit (with C wire) without any problems. When i tried the second one, the unit first told me the Rh wire was not connected. if i remove the c wire, it recognizes it just fine. i restarted system several times and tested my wires, which are all fine. now the unit tells me the c wire is not recognized. i can swap my units between upstairs and downstairs and i get the same results, likewise, if I swap the base units the one that was working continues to work but the other one has the same issue. so it is not the actual electronic unit. it seems the base unit is faulty.  i contacted Google to see about a replacement base, but they insist it is because my zoning and tell me i have to have Nest Pro come and install.  If i bypass my zoning, the unit still does not work properly.  Google hung up on me when i insisted i did not need Nest Pro help.  Any suggestions other than getting a new base?