Tado thermostat not triggering boiler

[Ian is stumped]

I've had my tado system in my new build for 5 years now and it's been fine. Yesterday morning I changed the batteries on the second floor thermostat and now it's not switching on the boiler to heat that floor. The thermostat display is fine and the app is fine. All systems say they are fine and connected.
It clicks to initiate the boiler, but it doesn't respond. We have replaced the thermostat, but it still doesn't trigger the boiler.
The ground floor thermostat still works, so I'm a bit stuck.
Any ideas?

 

[Basher]

I'm not too familiar with Tado, but it sounds like the second floor thermostat has lost communication with the boiler receiver.
The app probably gets its data directly from the thermostats, so will show whatever the thermostats are transmitting, but the boiler receiver may not be hearing from the second floor for some reason.
It could be a pairing issue, particularly if you replaced the stat, as you may have to delete/clear the old one first before the new one will replace it. You may have done all that of course! Have you been through the pairing process between transmitter and receiver, eg with the old one after it stopped working, or for the new one?
And you could try bringing the second floor thermostat downstairs close to the receiver to check it is being received and will operate the boiler from close proximity, which would indicate the problem is signal strength, interference, or something now being in the way of the original transmission path.

 

[gmartine]

Try restarting the Internet Bridge failing that contact Tado support or community.

When you say it clicks to initiate boiler does the receiver's heating symbol actually light?

 

[Basher]

Ian
Following on from the above, you say "It clicks to initiate the boiler"
What is the "it" that clicks?

Is the system radiator heating or underfloor?