Chosen Solution
I just changed the battery of my macbook pro retina mid 2012. The thing I noticed is that now that I turned back on, I have all lines on the screen. The strange part is that they come and go. I mean, sometimes the LCD screen works flawless, and sometimes it is just full of lines. It can depend from the battery? Cause once I use my old one the problems seemed not existent. How should I fix this?? Update (05/22/2019) So, everything now works just fine (monitor). The only problem is that the macbook won’t recognize the battery. I have tried everything, but it doesn’t work. There is anything specifically I have to do so that it works? First worked, then was plugged battery showing but it said not charging. Now I can only use it without battery even if it is inside(10 seconds power button, and plug the charger and it turns on).
Note: when I have the battery and the charger plugged in, the fan start spinning a minimal speed. What should I do?
According to your update it seems the screen has no more issues, right ? What you’re doing to start up the Mac is a SMC bypass, it works to see if Mac can boot but shouldn’t be used, unless for shorter times, as SMC is essential to run things correctly..try an SMC reset instead. If that doesn’t help unplug the battery from the board and see if things get back to normal. Unless you already glued the new battery in place it would be useful to reinstall the old battery to narrow down possible causes of your issue. It might be a faulty battery or a faulty SMC circuitry at this stage and without further info.
To help isolate the issue hook it up to an external monitor and see if the line appear there. If so, this may be a GPU issue. If not, an internal connection issue.
