Is it possible for a Teensy 3.1 microcontroller to receive USB keyboard input

I did not figure out how to do it from teensyduino (aside from having it also be recognized as storage in addition to keyboard). But I did find out that if you skip the teensyduino and just edit C files and compile them, then manually load the hex file to the board it work just fine as a keyboard on android and PC.

Here is the page I used most to get it set up: http://www.pjrc.com/teensy/usb_keyboard.html

I'd still be very interested if any one knows how it can be set up so that it will work from teensyduino.

USB ports should be capable of surviving short-circuit, but unfortunately, there are motherboard manufacturers which interpret the standard in different ways. Some will simply turn off the port, others will allow limited current to go through the port, some will have no protection at all.

Unfortunately, if you're the owner of one of the badly designed motherboards, there's no safe way for you to test what would happen.