Hello,
Welcome to
FixYa.
Based on your description it is likely a faulty control board, unfortunately. Here's what you can do to check...
**Turn off any power to the unit...safety first**
You'll need to access the control, this is best done by way of removing the front panel, i.e.
Once to this point, identify the wires on contact PF2 and inspect the closest relay to it, which will be K1.
If you are capable, measure amperage from PF2 when the unit is idle there shouldn't be power present, you'll require an ammeter.
Having said all that, it may be obvious when you visually
inspect the control, if it's burnt up or if the relay looks burnt inside.
This is an example of a damaged control but it may not be as extreme with a heater relay defective...
Let me know what you find and I'll try to help you further if necessary. For the control should be available at "repairclinic.com"...but if not let me know I may have one left.
Good luck and thanks for choosing
FixYa.
Regards,
Macmarkus :)