Nest thermostaat heatlink werkt niet

[Marianne]

Suddenly our Nest Thermostat lost connection and error H72 is shown.

We checked the heatlink and none of the lights were lit up.
We tried to reset it by pressing the button but nothing happened.

The Nest thermostat went off after a while because it did not get power trough the heatlink anymore.
We can charge the thermostat separately when connecting it with USB directly to a wall outlet.
So the nest thermostat itself does not seem to be the issue.

When connecting the heatlink to USB the lights do lit up. The top light is yellow and the bottom two are lit up green.
And we can turn the heating off and on by pressing the button on the heatlink.
Even when the heatlink is powered on via USB the Nest Thermostat still did not connect and turns off after a while due to not getting power.

We tried resseting the heatlink by pressing and holding the button on the heatlink but after rebooting it still gives the yellow light.

So with this information it seems the heatlink is the problem and it does not get enough power to connect the thermostat to the heating boiler.

[Frustratedddd]

First of all remove the USB out of the DATA socket you have plugged into, as that could cause you far more issue!! Why would you plug a cable into a data socket if you don't know what you are doing???

The reason you are getting a yellow, and 2 green lights fed via usb is, they are picking up the feed from the usb power supply. I expect when you try to reset, the lights go out, and you then put the usb cable back in and the light come back on??? Magic!

The ONLY way to prove the Heat Link is faulty is via a L/N test at the incoming terminals, No Power to those,  and you have checked the obvious source supplies, you Heat Link is duff.