Arduino Mega won't work at all

Hi guys,

I did the search here, and I didn't find anything similar... So my problem is, I connect the Arduino to computer and it does completely nothing! No lights appear, computer doesn't recognize the board, though sometimes, after leaving it still for about 15 minutes, it all suddenly turns on and after like 10secs - off again. I have used the board for like half of a year and nothing even similar happened to me before! I used the board with a home-made shield, but I checked the shield with a tester - nothing seems to be short-circuiting, and the shield itself has been working fine, though I have some suspicion that I may have accidentally mixed GND pin with VCC pin when connecting infrared sensor to the shield. I tried several different USB ports and even computers - the same everywhere.
Does this make ANY sense to you? Is there any way to save my board? :slight_smile:

Any help would be appreciated,
Thanks in advance,

You may have damaged it. You could try the loop-back test (see sticky). There are a number of components that could be damaged, in particular the CPU and the USB interface. From what you describe I'm not too hopeful. Those surface-mounted boards are hard to fix.