british gas wr1 isnt responding to transmitter to fire boiler?

hi changed batteries in transmitter and followed the instructions to initialise the two. After turning off the power to the wr1 and removing the batteries in the transmitter and then turning back on the power to the wr1 the light goes red, but when the overide button no2 is pressed the light does not go green nor the boiler fire. Im sure this is where the problem is. I then continued to initialise them to check they are communicating with eachother and sure enough when the batteries were replaced the red light flashed for 7 seconds confirming the radio signal is being sent and received. The lights then go to the on light being green and the receive/alarm light being off (but intermitently flashing red). Anyone help? Only had it 6 months and it worked fine last night and today not. Thanks