Can not recognize Nexus 7 2013 version with USB I am using android version 6.0.1 kernel 3.4.0-gad29d11. I have tried a laptop with windows 8.1 and desktop with ubuntu 16.04. I have tried installing ADB software and google drivers, using different usb cables, putting the device into developer mode with usb debugging on and MTP active, a galaxy 3 phone also is not recognized on either computer. Linux does not show a new usb connection when N7 attached and windows does not show any unknown/android device in device manager. All other usb functions (e.g., OTG operations, charging, etc.) work with the N7. 

What can I do?
I have had this problem on a labtop of my mom's. Maybe there is some security feature on the mainboard, I could not try it on this labtop because it is not mine, but that might be the issue. Look out for secure boot for example. (it would be interesting to know if it is a Dell, if yes this could be an issue referring to the company or kind of bios/uefi) I have tried it on another pc, desktop this time and I did not have any trouble. So if there is no option to fix it in the bios, just use another pc, (preferably a desktop) and flash on this system if you can.