no usb host!!! topic

I have a nexus 7 WiFi 16 gig refurbished from wallmart. Using for a car install, tried 3 different otg cables confirmed working on n7 2013 and made my own cable with external power and no go. Host mode will not trigger. No mouse, USB ,SD........ I get no notification that host mode is entered. Tried USB ROM, vanir, cm11, bs harmony, stock, every kernel. Still get nothing. Any ideas? Have power and volume soldered to some momentary switches. Any ideas I was thinking of trying to trigger host by shorting the pins on the tablet itself! Bad idea? All connections in the tablet look good.I am at a loss. Any suggestions are appreciated!!