The other LEDs can be seen using a digital camera or webcam. Most of them are sensitive to IR light. But if the green LED does not light, then the processor is probably not running.
One possible cause is that something short circuited in operation and burned out a component. Another possibility is an electrostatic discharge damaged the processor. This is a hazard working with sensitive ICs in the winter months. We do have replacement processors in the store: http://www.adafruit.com/products/75