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Is the fuse burning ever since you replaced the new board, is it possible your wiring is wrong?
It is clear that you have a short with the limit sensor circuit, inspect all wiring and sensors,
I am thinking that you got a defective board with internal short.
OK, Then a close inspection of all wiring (burnt wire touching to ground)
Follow wiring diagram to all components for possible error.
They are just on off switchs, no load, but may have resistance if contacts are dirty.
Load components are gas valve, and relays
Just by chance, try disconnecting control wires that go to AC or heatpump if you have that.
Y , C, O, R terminal on control board of furnace.
AC, OK forget that.
I think that you did not find a shorted wire or component, using a ohm meter should help you find it if you are familiar with diagnostic proceedures.
All wiring and components, if you are familiar with diagnostic proceedures. I am sure you can find many videos on youtube to teach you how.
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