Too true !
Always best to get a second opinion from them !
Even if you're convinced your right. Once you buy the board, it's yours as you no doubt know.
I've had the same experience. It's hard work sometimes and pot luck who you get. One day it can be a field engineer who is experienced and knows the job and the next can be just the opposite.
Try checking the live neutral for 220v first and then the other wires for DC voltage , I think you should get around 5v on these . If you can disconnect the low voltage wires and fan still runs then it's a faulty fan . Hope this helps.