I was working on interfacing an Arduino Mega with an Irobot Create platform, when for some strange reason i got a power surge on the USB port and the Arduino shut off seemingly for good.
When plugged in, the big overcurrent inductor (in the image below) on the board would quickly heat up, the board wasn’t recognized by the pc and no lights came on.
After thinking what could possible be wrong, the voltage regulator came to mind. It takes whatever voltages go into the power supply and brings it down to 5 volts that is needed for the ATmega chip. The regulator on the board is the: MC33269D-5.0
Go here for the datasheet:http://pdf1.alldatasheet.com/datasheet-pdf/view/12048/ONSEMI/MC33269D-5.0.html
it comes in two packages that do the same thing but look a little different, your arduino may have either one.