I have did something stupid.. I connected 10K Ohm potentiometer at its maximum value PARALLEL with a LED. The positive long leg of the led to arduino 5v and the negative leg to the GND. After giving arduino 5v from USB Mobile Charger ( Output: 5V , 1A ) I smelt a burn and quickly removed the charger from the outlet. I waited a few hours and connected the arduino ( without any components ) to the charger again. and the arduino worked. I then connected it to the PC and uploaded the blink sketch of the on-board led and it worked ! Then I uploaded a sktech for blinking led on other pins and it worked also !
My question is: 1) What is damaged on the board ? The smell is near the regulator but I'm not sure if it's from the regulator itself or just a component near it.
2) Can it be safe to still using the arduino board on USB Power or Battery Power without any problems ?