I've got a nexus 7 that I'm installing into a dash. I've bought an OTG Y-cable with power and a rosewill externally powered USB hub. I'm running USB-rom on the nexus 7. I plug everything in, power to the Y cable, power to the USB hub, and hub to the tablet. When I unplug the power from the USB hub it still remains powered on by either the tablet or the incoming power to the Y-cable. Is it possible the Y-cable isn't correctly wired for this setup?