Was it an auto or manual Rawrscary sir? What way were you refilling or were you using prefilled? Are you sure you didn't burn out the usb hub? Sorry for the multiple questions, but just trying to narrow down why it died. As for 5v being too much, suggest going with a higher ohm carto. The higher the ohms, the lower the current draw, the lower the wattage....
Just a heads up sir, you're in the V4L subforum, not the best etiquette to discuss other vendors here...