You may have a motor or damper actuator (solonoid) that has a partial shorted coil winding or possibly a bad ground; causing exessive current draw. The item will appear to work, just draw more current and get a little warmer than normal.

This added draw is likely more than the traces on the circuit board can handle. If it is only a blown trace, the board should be repairable.

Has only one function stopped working? If so, then the motor/actuator (or its ground) that stopped working after the circuit was burnt is your likely cause.

If not, you need an amp meter (not volt meter) to test the current draw of the various motors and actuators. If you have several identical motors and actuators, you can test the coil resistance of each (with an ohm meter) and see which one has low resistance.

The reason a fuse hasn't blown is because the excessive current draw is too much for the trace on the circuit board to handle, but less than the rating of the fuse for the circuit.