Here is info on this unit.
https://drive.google.com/drive/folde...0pXTTlDcGlXUWs
I am assuming that you have already checked the vent system and air flow and that it is OK.
There is not much you can do to check the board as appliance companies usually do not publish schematics of the boards.
Did you check to be sure that the heater element was not shorted to ground?
If not I would check that.
Unplug the unit and both wires from the heater.
You have already checked the resistance and it is OK.
But check from each side of the heating element to it's case, both should be infinite ohms.
If not the element is grounded and the heater needs replacing.
I would also check the heater relay.
Unplug the unit and the wires from the heater relay. ( both relays if it is a dual element unit)
Then measure across the relay contacts.
Should be infinite ohms.
If a low resistance then the relay contacts are welded together.
Either the board or the relay needs to be replaced.
Finding just the relay may be difficult.