That Nest will not control a humidifier so you need to put the wiring
back the way it was. Look at page 16 of the installation manual -
https://www.behler-young.com/UserFiles/Resource/APRILRINST00076.pdf
With that thermostat the blue B wire would be a C for Nest.The black
W2/X2 would be an E wire in most cases - used for emergency heat. Best
to find the wire at your air handler and see what it is connected to.
Most times it goes to the same place as ...
