I recently got the Smoothie board. Today when I was going to set it up, it worked for a while, I was able to move the motors and heat the bed (did not actually print anything). However, after experiencing some problems with the extruder I tried replacing it with another motor, upon turning it on the usb was not not detected. I have tried reformating the sd card and have even installed a new one with a fresh firmware and config file, removing everything from the board, but still no luck. Only the 3.3v led turns on (the four other leds seem to turn on for a period after ejecting the sd card and reinstalling it but promptly turn off). Also the main processor on the board gets rather hot (uncomfortable to touch for after a short time) when plugged in through usb. What is the most likely problem with this board and how can I fix it?

Thanks for any advice :)