Ouch- yes, the 15 amp fuse is a bit high for the board. The fuse protects the entire low voltage system, which runs from the transformer in the furnace, to the indoor board, to the outdoor unit, to the thermostat, ect. The low voltage system controls the entire heating and cooling system. As to which components in your system are bad, it just depends on where the short is (as this is determins the channel that the excess amperage flows through)
The board itself may or may not be bad. The main transformer in the furnace, which converts the high voltage into low (24) volts may have blown. It may be a variety of other items also.
I'd start by seeing if you transformer is still producing 24 volts on the secondary side. If not- its bad. If so, the hunt continues. Hope this information helps you get started!
NorthAmericaHVAC.com
Joe
P.S.
We have a large variety of OEM and universal transformer and control boards in our store if you end up needing these or other repair parts