I was working with the pipe gas lines so I did shut off the gas and the electricity then I finish to work and I turn the gas back and the electricity the furnace fan start working and stay for a long time on and in the morning I find out that no heat coming out off the furnace start5 checking and on the circuit board the terminal w and c don`t have 24 volts and the thermostat also does`nt have electricity what can be the problem.