Chosen Solution

Hello, I am working on fixing up a computer from craigslist for a friend of mine. I replaced the HDD with an SSD and it was working fine. I ran AST and VST yesterday and both of them passed. Today I took out the logic board to reapply the thermal paste before I finished updating the computer and once I put it back together it won’t boot. I get the startup chime and then a black screen. I have checked the connections and they all seem to be seated well on the board and I made sure not the screw in the Processor and GPU’s heatsink too far. I’m out of ideas and if anyone else would have any that’s great! I am getting the correct boot chime as well as the ability to reset PRAM. I’m having some problems keeping the keyboard plugged in so when I get home from work I will try an SMC as well. Any help is appreciated! Thank you all in advance!

A 15” Pro from 2011 ? Sounds like yet another dead GPU to me..same issue on the external monitor confirms it. Not much you can do with it besides replacing the board or putting it back to Craig’s where it came from.