My Nest Thermostat is not able to connect network and search any available network. Keeps showing W5 error. The issue is not recovery. Even I reboot Nest device, the error code is still showing.
Contact Google customer support. They will most likely tell you to purchase a new one.
If it has worked on wifi before it may have had a power cut or wifi outage. Reset thermostat and heat link box and see if the heat link then finds it. If not you may need to pair it again to your wifi
Google Nest Help Center
Chromecast Help Center