I bought the heater a few days ago. No instructions were included. Please e-mail a manual to me. Or answer this question: The heatre worked fine the first day. Now it will start to heat but only at 64 degrees F. When I try to raise the temperature to say 70 Degrees, it will flash at 70 for a few seconds then return to 64. This did not happen the first day.I do I fix this? Please respond.