New RepRapper, LEDs are alive, motors are not moving

Software - Marlin, Arduino, Repetier.

Chips - Ramps 1.4 with an overlay board for stepping, plugging-in motors and thermosisters.

The motors provide much more resistance when it is plugged in (i believe they are powered)

Trying to find "home" in manual control, using recommended settings. The Prusa is "connected" at the top left. The motors don't respond, buzz, jerk, anything. They're just chilling..

The mechanical end stops seem powered too, when clicked an LED lights up.

I checked the wiring 3x before plugging in, but am about to undo everything and re-attach. Is there anything obvious I should check first? Any good how-to-guides I should read or anything?

Thanks!

Update: I had wired the PSU wrong, the components were being powered via the 5V Arduino USB connection. My lesson was that if the PSU has an LED, and it is plugged in and not lit, it may not be powered.