Having issues upgrading a 2011 with a 2012 logic board, RAM & SSD.

I’m having similar issues, have tried smc and PRAM resets and it powers on only when connected and it’s black screen, MagSafe doesn’t turn orange even tho I know the battery is out of charge, was brand new but only had 7% when I turned on the computer to test everything worked.

My issue is that I get black screen every time even when I plug it into external monitor. Swapped logic board to the 2011 version of the high end board; like 2.7 i7 is for 2012, and the display work on that one. I’ve read online that GPU is most likely issue because a LVDS issue should only affect the display it’s connected to and not an external. Gonna try cleaning the GPU again but this time going to check under the tape and see if that resolves it.

I get black screen on display and external monitor. I know it worked when I tested it, once I knew everything was good I swapped the RAM and SSD from my 13” 2.5 GHz mid 2012 to the 15” 2.7 GHz mid 2012 and that’s when the nightmare began.

Have put the hard drive that it worked with the first time along with RAM but it doesn’t work anymore. Tried 3 different sets of RAM, different combinations, 1 slot in the other empty, battery connected/not connected.. Literally cleaning this out is probably going to be my last attempt before I shelve it till I have a bit of cash to take it to a board repair place.

Might try placing the heat sink from the 2011 board that I know works.