Mac won’t turn on after screen replacement

When this happens simply disconnect SMC ribbon cable and pancake battery screw first, then unclip all the Connectors that are accessible when back cover plates are removed... wait a few minutes. Reconnect all Connectors and protective plates then, the pancake battery screw and SMC ribbon cable. Turn MacBook over insert charging cable and lift the lid, your MacBook will turn on... after Initial start up it will turn on with or without charging cable connected

Ouch! I haven’t encountered that so I just don’t know. I think you’ll need to bring the system into Apple when they reopen.

Take some pics of the logic board markings as well as the systems S/N number, so when you get the system back you can see if they exchanged out the logic board.

So I did this and still no change on the screen I hear the boot up but I didn't get a screen turn on or anything please help

Please help.... same issue here but I can't afford to pay for $800+ professional fixing after already paying $500 for the replacement screen..... won't turn on backlight/screen/touchbar, and I even replaced the SMC ribbon cable :'(

Before I replaced my screen following these instructions, I knew the problem was the ribbon cable that I'd damaged trying to remove the Macbook Pro strip at the bottom of the screen - so I knew the computer was fine.

I followed these directions to the letter, but ended up with a computer that wouldn't power up nor charge by the end of the job.

After taking the computer to a professional, I learned that I'd unknowingly blown a number of chips on the logic board because I didn't adequately ground myself before doing the job. So, I saved a couple hundred bucks replacing the screen myself, but had pay hundreds more to get the chips replaced at a "non Apple certified" repair shop, and the "authorized" shop in town was just going to send it back to the Mothership to get the job done cheap and easy for the flat Apple fee.

The local shop did the work and fixed the problem, and was able to maintain all the data on my hard drive. Apple was going blank it out 100%.

So, lesson here is to ensure you ground yourself before doing any job you see here in iFixit.