Not sure how much your aloud to abuse it before they wont take it back but i have lots of fans where i cut off the plugs, took the positive wire, stripped the end and put it into the yellow female end of a Molex plug. Same with the negative and it connects to the black right next to the yellow. That worked for me.
If they dont work when you do that then they probably wont ever work.
If they dont work when you do that then they probably wont ever work.