Black Screen on boot - May not be detecting external

Carefully disconnect your systems battery following this guide MacBook Pro 15" Unibody Late 2011 Battery Replacement Stoping at Step 4. Now press and hold the power button for 15 secs so you fully discharge the logic board. Now carefully plug in your MagSafe charger, press the power button, and then press and hold the T key. At which point you should see the FireWire or Thunderbolt Icon on your internal displays screen. Do you?

If not plug in your external display. Did you see it then?

@tjones123 - Sadly your logic board has had it. This test was to see if we even can get the CPU's graphics engine to work. Someone with deeper skills might be able to replace the damaged components. In the end you won’t get a better GPU which is the weak point in this series.

At this point I think your best bet is to replace the logic board. Now you could go for another 2011 board or what I strongly recommend is jumping to a 2012 board. This is one of the rare cases this is possible! Apple put a better CPU and GPU chip on the 2012 board. In fact I’m banging way on such a converted system right now.

Here’s the needed part:

• 2012 15” Logic Board - 2.3GHz i7 - Apple P/N 661-6491
• 2012 15" Logic Board - 2.6GHz i7 - Apple P/N 661-6492
• 2012 15" Logic Board - 2.7GHz i7 - Apple P/N 661-6493

And here’s the guide to put it in MacBook Pro 15" Unibody Late 2011 Logic Board Replacement. This is one slight modification needed to the LVDS cable

The tricky part is finding the part! Even the 2011 boards are getting hard to come by as well.