I have burned or melted connection to my circuit board

• The main terminal block where the incoming power terminates has burned/melted 
• The copper straps or wires connecting the  circuit board to the heater have burned or melted 
• One or more wires that connect to the circuit board relays or termination points have burned

All the above were caused by a loose connection. If this is a new installation, the nut/screw were not secured tightly enough, thus creating resistance and heat. If this is an original installation, then vibration may have caused the nut/screw to become loose over time creating resistance/heat. 

Please note that if this is a new installation, the manufacturer does not consider this type of damage a manufacturer defect and will not cover it under warranty. It is very important that you make sure all nuts, screws and terminations are sufficiently tight before powering up the system.