Thermostat nest 3 generation

[11kuhadas]

Hi there my nest shows the temp we choose but it is not triggering the radiators neither is the boiler firing We went away 3 weeks put away mode and now it is not working . We went through all the issues stated and tried it , came on for 10 mins then went off again and refuses to start Even my neighbour who is good in these tried no joy Can anyone help please as we are 70 and house is freezing 

[Frustratedddd]

Are you in the UK and using the Nest with  Heat Link and display?

Should that be a yes, do you have any lights on the Heat Link, and if so what are they? Does the display show any errors at all? Have you tried turning the display to call for heat above your desired temp, and if did anything happen?