Danfoss RX1-S (CH override button not working)?

I have a Danfoss RX1-S controlling my hot water the cylinder stat seems to be working ok. The thermostate shows 40C have set temperature to 60C the stat is showing asking for heat the wifi connection shows healthy, but it is not operating the RX1 to open the valve for the hot water. tried pressing the override CH button this brings the red light on but only for a few seconds
ant ideas