My old honywell thermostat model #T8411R 1028 (2) appears to have died. I purchased a newhoneywell thermostat model #RTH7500 series. It was working until I changed the temperature and it stopped working. It keeps making clicking sounds but is not coming back on. I am now waiting for an expensive cooling and heating service to come out tomorrow and meanwhile we are miserable in the house. Any suggestions for what I am doing wrong?