Nest thermostat and Heat link won’t connect H71 error

[Ermintrude]

Hi there

We have recently moved into a property with a nest thermostat and heat link.

We have been left no instructions so are a little confused! Since my husband removed the previous people’s account and tried to reset the thermostat to input our heating preferences etc we are now getting the h71 error that the thermostat won’t connect to the heat link. We have tried multiple times to reset both the heat link and nest thermostat. 
Can anyone help at all? 
Thanks 

[Frustratedddd]

First questions you need to answer before we get in to deep.

I am assuming you have a 3rd generation thermostat, but if you don't know upload a picture.

1. The H71 screen should show a list of options, can you see Technical. Look in there and see what the 6 digit number is for the Heat Link. Make a note of that.

2. Now check at the Heat Link and remove the front cover, look on the left hand fixing screw you will see a 6 digit number. do they match?

3.How did you reset the Heat Link? exactly how YOU did it.

4. How did you reset the display, how did YOU do it?

Without answering all the above correct pairing will be very hard.

Have you searched this forum how to pair also, as this has been covered many many times by me?