The first node is status from the switch everytime it is initiated.
The 2nd node is a function node to change the colour of the light switch on the dashboard (i.e. press it once, it's green (on), press it again, it's red (off)).
The 3rd node is the UI dashboard button
The 4th node (this is where I am stuck), needs to turn the light on/off when pressing the same UI dashboard.
The 5th node is passing the payload from the 4th node to the light switch.
It sounds as if what you actually want is a switch not a button. Then you will not have to mess about making it toggle, and will have feedback as to whether it is on or off.