Blower motor is easy to test from the connector on final stage. First measure supply voltage between pins 2 and 4. Then with two jump wires connect the voltage and ground directly to motor, pin 2 -> pin 5 and pin 4 -> pin 1.
The female pins on that connector can loose tension and connection over time. So when the connector is out clean the pins and use some contact paste. On my own X5 the problem was poor contact on that activation line from IHKA to final stage. As this is only low amp signal line there were no signs of over heating despite the poor contact stopping the motor.
https://bmwteka.com/wds/en/e53/e64507f5