Thermal fuse? Never seen one in a refer circuit.
What model of Domeric refer?
To operate it likely will require,
12VDC for control voltage,
Propane or 120VAC for heat source.
There should be a fuse at the fuse panel for 12VDC and a breaker for 120VAC. There should also be a fuse on the control board.
If your blowing a 12VDC fuse that likely means either your control board is shorted out, or you have a frayed wire shorting to ground. Time to get your volt meter out.
BTW if you believe the board is bad, look for a Dinosauer board. They are better built than the factory parts.