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I am new here and have a question regarding black screen on a MacBook Pro early 2013. A few weeks ago I updated to Catalina and just some time after the screen went black. It chimes at startup and sometimes the screen lits up with the Apple logo and the startup boot line. When the boot is almost finished the screen blacks out. I can see the login screen and be logged in and work on it by screen sharing from my mac mini. But I can’t see the booting process or go into other modes such as disk utility or restore from the mag mini. I have re-installed catalina with no luck, and I seem not be able to reinstall an older version as mojave. It gives an error that the installer is too old.

Battery is exchanged and screen cable attachment to the main board has been checked.

Any clues of what it can be? I would like to install mojave just to be sure that catalina is not doing anything, but I have no more ideas of how to proceed.

Additions as of 27 December. I thought I solved it with switching of GPU. I managed to get full startup sequence with functioning screen. But I can’t reproduce it. I am trying gswitch and it does not matter if I use the internal or discrete GPU setting. Same black screen and intermittent pattern of Apple logo visible during startup. I noticed that when it started up normally there was a slight dimming of the Apple logo, at the same time spot as the screen shuts down. So there is something in the startup sequence that does some switching of GPU; either is works with some slight dimming or it gets black.

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  • Shine a light through the Apple logo on the LCD cover. If you see an image, then your backlight and/or its circuit is blown. How did you have the LCD flex cable checked?
    – Allan
    Dec 27, 2022 at 2:41
  • Screen is completely black. When booting up, it lights up a bit, the Apple logo shines including the start-up bar. At the end of the boot-up it shuts down, I do not see the login screen. It shows only via remote, screen sharing. I checked the screen cable contact on the board side for any dirt or corrosion, cleaned it by inserting it and removing it a couple times. No luck. I have yet no clue of how to reinstall an older OSX, Mojave.
    – Thomas_A
    Dec 27, 2022 at 10:09
  • “Lights up a bit” is indicative of a backlight issue. The backlight is responsible for making the image visible and for the brightness level. If the logo is the cirrect brightness when booting, and then it all stops when the booting is complete, you have a GPU issue. It needs to go in for service.
    – Allan
    Dec 28, 2022 at 3:17
  • Sorry, what I mean is that the screen lights up a bit at startup. There is no hint of image through the front lid when the screen is black. Despite one successful startup, I have not been able to repeat it with the gswitch GPU switcher. I have also tried the pmset function in Terminal to no luck yet.
    – Thomas_A
    Dec 28, 2022 at 8:42
  • I suspect a bad solder joint of the GPU Vcore chip. I will give a try to fix it. If it works out I will report back.
    – Thomas_A
    Dec 28, 2022 at 13:23

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Removed main board ans resoldered the GPU vcore chip. It is now alive. So it was the classic solder joint break. I guess this happens at some time with lead-free solder.

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