I am sorry you are having problems with your VNH5019 shield. However, the blog is not an appropriate place for troubleshooting your problem. Instead, you might post this on our forum with more details about your setup.
The A* 32U4 should work with many of the Teensyduino libraries. The biggest obstacle we expect is that the pin mappings will be different. For others that are interested, we are discussing using the Teensyduino Keyboard library with the A* in this forum thread.
Feel free to keep us posted on any of your progress involving other Teensyduino libraries and the A-Star.