Bingo!! That did it! Thank you so much for your help.
Just wondering- could I get a jumper to join 3 and 4 on the PCB to do away with the wire and dead Salus completely?
I have a Potterton Titanium 33 and the central heating didn't come on with the recent drop in temperature. The Salus BC600RX started to blink red intermittently and then starting clicking continuously. I tried reseting the transmitter - nothing, so bought a Hive (which we were considering...