Bathroom fan runs despite switch is off
The thermolec is a make up air duct heater , the lightning strike may have damaged the control board is the occupency sensor causing the fan to run as long as there is power. I would turn the breaker off pull the controller (switch) and disconnect its power  if the fan stops you know where the problem is the switch. If the fan continues to run with the power restored and the switch disconnected the thermolec duct heater may be controlling it and that would be the next item to remove power from the controller (with the power off). I would guess the occupancy sensor part of the switch failed.