Hello!
This week I've got a new Arduino. That was so interesting to explore it! But after a few days it stopped working. The voltage was correct. After that board cannot be reseted and it isn't seen by Arduino IDE, +5V and GND pins are shorted. Sketch is not working too. Also I found that capacitors PC1 and PC2 (or one of them) become overheated after couple seconds of work. Is that problem of Atmega or other electronic components? Tell me if I can provide you some information about problem.
Do you have the capability of changing the capacitors? If so, there's no harm in trying (unless you want to return the board to the seller). If not, there's not much you can do other than replacing the board anyway (other than trying to prevent it from happening again).
Is there a chance you've over-voltaged-it?
Did you power it through the barrel jack, or directly to 5V, or USB?
PC1 & PC2 are "isolated" by the voltage regulator, so it's unlikely that both would be fried. (But, bot have could have been installed backwards.) Since the 5V side is shorted, it could be PC2. Is the part burned or discolored?
A reversed electrolytic capacitor can sometimes "work" for awhile before it shorts-out. It could have been a manufacturing defect. Check to see if PC2 is reversed (if it's not burned to the point where you can't tell).
It's a big clue that the capacitor got hot, but otherwise a 5V to ground is very difficult to diagnose because almost all of the components are wired between 5V and ground, and it could be "anything". Usually, it's an active IC (because they can be easily blown by over-voltage, reverse-voltage or static discharge), or it's an electrolytic capacitor (because they can also be blown by over-voltage or reverse-voltage) and they often fail as a short.
If excess voltage was applied to the 5V circuitry, there's a chance that more than one part (including the ATmega chip) is fried.
You could carefully unplug the processor from its socket and see if the 5 V line still seems to be shorted. That will tell you if the chip is blown.
Have you checked the voltage across each capacitor? The first one should still have voltage across it even if the chip is blown or the second capacitor is shorted.