Nothing happens?

Hi guys!

I've been involved with 3d printing for some time now but never got into the DIY open source projects. I finally took the plunge and sourced/printed the pieces to build my first prusa Mendel i2. I have everything together, everything slides smooth and is measured out.

I got my 30A power supply yesterday and spent a couple hours finally running wires and connecting up the ramps1.4. Plugged everything in and nothing happened. I tried plugging in the USB and I get an error about the USB hub being overloaded and shutdown. It was an older MacBook Pro so I thought maybe it was the age of the computer. I unplugged the arduino from the ramps and took it to my windows computer to load marlin on it. The computer saw it and I was able to load it up. Went back to the printer plugged the ramps back in and... Nothing.

Is anything supposed to light up at least so I know it is alive? I have an LCD hooked up and thought I changed the config for the gadget3d LCD panel but it doesn't light up or show any signs of life. The arduino LEDs don't even light up when connected to the power supply. The power supply fan and led do turn on though.

What is supposed to happen when powering up for the first time? THANKS!

Connect to the Arduino via the USB without the 12V and see if you can connect to it.

Make sure you pay attention to what COM port the Arduino Software is attempting to communicate on, and that you have the Mega 2560 selected.