But I don't work here. Ask the people that work at Piper, they'll help.
Friend of the "therealpiperbot": If you have another monitor I would suggest seeing if you can connect the other monitor to the raspberry pi to see if the problem is the screen or the Raspberry Pi.
We recently put ours together , and I noticed a couple of things with the screen, first the ribbon cable going from the screen to the board mounted on the back of the screen needed to be re-seated straight. Secondly, the other cable connecting the screen to the pi, as well as the cable from the power brick and screen, both needed to be inserted with more force then we were willing to give it a first.
It sounds like you have probably checked these already, but that is where I would start. Good luck.