Chosen Solution
Good day, my MacBook Pro has a very weird problem when it boots the screen lit up but no image when I connect it to a external monitor it works fine.. one day I power it down and close the lid plug in the external monitor plug in the power cord the Mac turn on I left it there in chrome shell mode for and extended amount of hour when I return I lift the lid, the screen was working fine on then if I close the lid it goes by back to square 1 does anybody knows what’s happening?
True you do have a wacky issue! We’ve seen this before in the older MacBook Pro’s. Your system can support an external display via any one of your Thunderbolt ports when you do the signal load is enough for the internal display to work. In the older models we found the logic board MUX logic was messed up. I’m suspecting that’s the case here. This will need someone with deeper skills to diagnose and replace the bad components the logic board or you’ll need to replace the logic board.
