MacBook Pro screen backlight but no data

[Valdaquendë]

I have a MBP that boots to a screen that has backlight but displays no data. The screen lights up to a blue-gray color (which I take to be the screen's backlight) upon boot and remains backlit as long as the device is on but no video data is displayed.

I thought that it might be a defective connection between the logic board and the display so I tried connecting a USB-C adapter and an external display. The external display behaves exactly the same way; it activates and shows a background color but, again, no data is displayed. The Caps-Lock key's LED lights up when pressed but there is no keyboard light, the touch bar is unlit and inactive and the device is otherwise unresponsive. Recovery mode cannot be invoked.

My preliminary conclusion is that the problem is in the logic board; I'm reasoning that if it were the display or its cable or connections, connecting the external display would bypass these factors, routing video directly from the GPU to the external display. The fact that neither receives data would seem to indicate that the issue is with the integral GPU or the other logic board circuitry.

If you know of any other potential explanation for this behaviour or any further tests or actions that might be more conclusive, I would be very grateful to know and try them. Thanks in advance.

 

[HobeSoundDarryl]

How old is the MBpro? Could the drive be dead? It reads like the OS isn't booting. Turn on, light up the screen, wait for OS... and it doesn't boot. Dead drive is first guess.

Have you tried booting into Safe Mode?

 

[Valdaquendë]

An excellent thought; thanks.

Unfortunately, the device is a Late 2019, so its storage is soldered in, making logic board replacement necessary anyway, unless I'm missing something.

I can't boot into Safe Mode or Recovery Mode. No Apple is displayed at boot. No chime. Can't reset PRAM either. It's like it is dead in the starting gate but with a backlit screen. If the drive were dead, I would expect to be able perform most if not all of those actions.

Thanks again, HobeSoundDarryl; I appreciate it.

 

[Valdaquendë]

Just so this is not some dangling thread, I had to conclude that my diagnosis was correct. I found logic boards priced from $300 upward. The process of R/R for the logic board is pretty straightforward and would have taken an hour or so but the client declined to do so.