Mid 2014 Macbook Pro Retina - Black screen on boot, no chime

I recently tried to install big sur on my macbook through a bootable USB drive. Everything went well until during the install the computer auto rebooted and showed the apple logo and load bar then went blank. I guessed the system was still installing so I waited 10 hours but still a blank screen. Now I have tried to unplug the USB and restart but the computer seems to be stuck in some kind of limbo. Here are the symptoms:

  • No chime when powering on
  • Backlight turns on but nothing is displayed
  • Fan spins
  • Ignores closing laptop lid (Fan still runs and backlight on)
  • No display signal (external displays say no signal)
  • USB gets powered on
  • Cannot boot into anything (Recovery, internet recovery, verbose mode, safe mode, usb drive)

I have tried:

  • Resetting SMC
  • Resetting NVRAM
  • Removing battery, leaving for an hour and reconnecting.
  • Replacing SSD with a working SSD from an identical macbook model. (still nothing)
  • Removing and wiping SSD using another computer
  • EDIT: I tried letting the computer sit with the screen blank to drain the battery as a last resort and now it will display the red low battery graphic if I press power on. But still no boot.

It seems base system is missing or corrupted. I have tried everything. What do you think?


Solution 1:

It’s the I/o, disconnect it and it will work again. Or change the I/o board. Tried it and it worked! Good luck