Elkatherm electric heater pairing issue

[Bob668]

Hi,
We have a number of elkatherm heaters installed and they are operated remotely via the HeatApp. However they have lost connection and now are not viewable via the app. Does anyone know how to repair them to the zones. Supplier states that the temperature button on each heater needs to be put to zero which starts the pairing process. No luck with this though

 

[Adam_151]

Looking at this: https://data2.manualslib.com/pdf7/3...?13a07201fe3c3d7e6ea02aba51cf8e01&take=binary
It looks like holding both up and down buttons until SP (spart pairing) is shown on the screen puts it in pairing mode