USB can't connect when Stepper Drivers are connected

First time build here, and I'm hitting an issue connecting my Stepper Drivers. This is a custom build based on the Prusa i3.

I am using a Sunfounder Mega 2560 R3 with Ramps 1.4

I've wired everything to Ramps 1.4 EXCEPT my Stepper Drivers, installed Marlin successfully, and I can connect Pronterface and successfully monitor heat, generate hot end and heated-bed heat, and get proper signals from my end-stops.

I realized that I was missing Stepper Drivers, and ordered 5.

As soon as I connect even a single stepper driver, I no longer get power to the USB on the board.

Any ideas what may be happening for a first-timer just learning everything?

Stepper drivers in backwards or out by one pin?

Pictures of your stepper driver and how you plugged them in might help (doesn't have to be on to take pictures)

Edited 1 time(s). Last edit at 02/19/2018 11:59PM by Dust.

I got a multimeter (which I should have done in the first place). When I have it set to measure DC mV I'm seeing pretty much nothing, so I am assuming I somehow blew all my drivers while the Arduino and RAMPs boards survived.

Ordering new drivers and a new RAMPS board just be safe.