Unity just hangs at the “pushing content to device” stage.
Occasionally I would get it to throw errors related to signing the application. I’ve set up a signing key, but that doesn’t seem to have solved the problem.
I’ve never done this before (I literally bought my first tablet four days ago), so I have no idea what’s wrong.
turn on USB debugging on Device - Settings/Developer/USB Debugging
Did that already! No dice! 
Are you able to see the device via ADB Devices?
I do not know what this means. I did have a hell of a time getting the MTP driver to function correctly and other than a “check for viruses” in the dev options, I haven’t seen anything related to ABD.
Try just building the APK, not build and run…then just transfer the file other to your phone and see if that works.
Draco, ADB is the Android Debug Bridge : Android Debug Bridge (adb) | Android Studio | Android Developers
That is why debugging should also be enabled on the phone, Unity uses the debug bridge to push the .apk file to the phone.
Now is the rest of that link not very important, but the part about the syntax is : “You can issue adb commands from a command line on your development machine”. So with command prompt, go to the android direcotry, and type “adb devices” there, which will give you a list of devices connected through ADB.
If there are no devices there, but you do have your tablet plugged in, then most likely, the wrong usb drivers for that device are installed. You can check what drivers are being used by looking at your Device Manager. If it’s using ADB, you’ll see a drop down option for ADB devices.
With these kind of problems, the ones where you don’t get any error, it’s basicaly a matter of deducing all the factors. If you can confirm the tablet is connected through ADB by checking the devices in the command prompt, then there is another problem.
Device is listed.
Trying a build, then copy manually, to see what happens…
Had trouble copying directly (Windows attempts to copy, then says it can’t find the file), but I was able to dropbox the apk and install it.