A: There is a fuse on the 24 V auxiliary power board, this board will provide power for fan and soft-start contactor. If the fuse damaged, the 24V auxiliary power board will not output 24V power supply, in this case, contactor isn't close, the drive still trying to start with the resistor in the circuit, there  will have a big current through resistor. But in most cases, it will not burn up, because our VFD has protection for that. I will explain more: when the power goes into VFD through soft-start resistor replace of contator, the resistor will act as an Partial voltage resistance in the whole voltage range, for example, from DC 540V goes down to 350V, our VFD will report "UV" under-voltage fault, to protect the soft-start circuit. In very few cases, the VFD don't have time to protect while during voltage from DC 540V goes down to 350V.

Sometimes, the resistance shell is cracked due to heating, its inside resistor may not be broken, I supposed that. You can use a multi-meter to test the resistor value is 20Ω or not.