UNO R3 Board won't connect

So I bought the Arduino starter kit, which includes a book with 15 projects. I connected my UNO-board to my computer and it lit up like it should. I then unplugged it and wired the cables as shown in project two ( spaceship interface) (and I know that I connected everything like I should, I have triple-checked) and copied the correct code to arduino.

When I then connected my UNO-board it lit up for a moment, then it just turned off and got really hot (still is). My computer got a pop up window saying "USB Accesories Disabled, Unplug the accessory using too much power to re-enable USB devices."

I tried unplugging it and then plugging it in again, changing cable, changing computer, but nothing works. (both were mac computers)

What could be the issue?

Sorry for my bad English. :o

Please post a clear picture of your project. If you click the "Reply" button, you'll see an "Attachments and other settings" link that will allow you to make an attachment. That picture might be helpful for us to understand the issue, especially since not everyone is familiar with the Arduino Starter Kit projects.