Nest 3 gen thermostat. Hot water not working

[OldReadingRoom]

Nest, third-generation thermostat. Hot water not working. Heating working normally. Continuity test and heat link. all working normally. Hot water does not respond either to app or to schedule commands. App turns red, heat link ‘clicks’, boiler does not activate, hot water/heating valve does not move. Have deactivated the legionnaires functionality on the thermostat and have rebooted the thermostat several times to no avail. Does anyone have any suggestions about what to do? Thank you. 

[Frustratedddd]

Easy way to prove the Heat Link is working for water, press the button on the Heat link, and see if that overrides.

Failing that, if you have access to a neon screwdriver, place on terminal 6. Make sure you only have one light on the Heat Link.  Check if the neon light is just glowing. Now press the Heat Link button to activate the 3 lights, and you will hear the contacts click. Check the Neon light, and should be brighter.

Basic, but easy proof if the contacts are switching.

[Janos79]

My nest went crazy too. It is working fine for heating however the hot water starts itself every 2nd night for 1-2 hours. No indicator in the mobile app, I can see a drop icon on the Nest display but I'm not able to switch it off. It drives me crazy now. It feels like Nest can use my energy when they think it is good for them or someone else.