aux fan quit working!!

recently my ac started blowing hot air on and off, then i realized that my aux fan quit working and overheated, but did not indicate rise in temp on the gauge inside. so it actually blew out my radiator drain plug, "which is the blue plastic one im assuming" and now i ordered a new plug but do not know how to go about testing to see if the fan is bad or a relay or switch is bad?

Might be a stupid question but did you check the aux fan fuse in your fuse box under the hood?

Sent from my C771 using Bimmer App

i didnt know there was a fuse for it. im new to bmw's and i was told that there is no fuse or relay for it. but i looked anyway in the black box on the passenger side by the firewall. is that it. there was no labels so not sure what was what, and more wires than anything.