I have a similar problem happening right now. Installed Nest Learning on 1 April. Ran heat through May, then AC and Heat into June until we went to straight AC for summer. Multizone heating system (forced hot water) with two Nest E's on other zones. Testing heating system from Nest Learning on 6 Oct. Taco box just kept clicking. You will see other posts about this across the web. Call heating company for PM b/c I assumed the problem was with boiler. First thing tech said when he arrived was "you have a Nest thermostat, correct?". He performed the same troubleshoot you did (W to Rh wire - triggered heat). Notified Google and then sent me new baseplate (arrived last night and installed - no fix. Same exact issues). Contacted them again this morning and just went through 2 hours of painful chat troubleshooting with totally useless reps (Madison and then Enzo). If you get them, stop the chat, pull the Nest out of your house and get another brand. I'm done with having a teenager in their basement ask me if my house is powered and calling it support/troubleshooting.
