Are you at least getting the Apple chime? If you get the Apple chime, connect an external monitor using the Thunderbolt 2 connector with a T2 > DVI/DP/HDMI adapter (whichever one matches your display) to see if you get a video signal.
If you don't get a video signal, I would try to do a PRAM reset with the Cmd+Opt+P+R keys. As long as the eDP cable matches all the connectors, it should work.