14’’ M1 Max MBP reboot loop with black screen

Question

MacBook Pro 14" 2021

Repair guides and disassembly information for the 14-inch MacBook Pro released in October of 2021, featuring Apple-designed M1 Pro and M1 Max SoCs. Model A2442.

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Tim Ole @timz19546

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crwdns2931729:0crwdne2931729:0: Dzi 6, 2025

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14’’ M1 Max MBP reboot loop with black screen

Issue Description

My MacBook Pro is experiencing a persistent black screen issue accompanied by a reboot loop.

When powering on, it plays the usual startup chime, but the internal display remains black. If I shine a flashlight directly onto the screen, I can faintly see a dim Apple logo (under 1% brightness), indicating the system is attempting to boot but failing at a very early stage—likely during the hardware self-check, particularly related to the display.

As workaround, I unplugged the built-in display cable and use an external monitor. Then every thing works fine, I just been using it as desktop for month.

Apple support suggested replacing the entire display assembly, which is their standard recommendation.

A third-party repair center narrowed it down to a potential LCD component failure and proposed replacing just the display panel.

However, I’m unsure if the LCD itself is the true root cause.

I need help determining the most likely root cause before committing to an expensive full display replacement. Thanks!!

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Dan @danj

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Self employed contract worker

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crwdns2931729:0crwdne2931729:0: Dzi 7, 2025

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The M Series systems have fewer parts as more of what was in discrete parts is now unitized into a single chip (SoC) and a few dedicated chips (RAM & Flash Storage) as well as the inputs and outputs we need.

Here a display issue is an output so while it is not showing an image straight out, it is not the direct cause of the system going into a reboot loop. The fact image is present using a flashlight tells us the video signal is getting to the LCD, only the backlight power is not present so the video can be seen.

So what we have here is a deeper issue within the logic board which is effecting the backlight power. So let’s dig a bit deeper what happened to the system before its current state? Did it get dropped, banged or even sit unused for awhile? Did it face an environmental event get wet or go between cool and hot spaces where condensation could collect (high humidity) did the system encounter a liquid spill or dust storm event?

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Thanks for the reply,

One thing I forgot to include in my description is that the 3rd repair did inspect briefly and found no apparent water damage, and it wasn’t dropped or physically damaged.

But he did swap the entire display assembly from another mbp of same model and found the booting and display works fine, hence leading to suspect of display issue and found the dimmed image using flashlight.

I don’t know if this info changes anything.

Thanks again for your help

crwdns2934271:0Dzi 7, 2025crwdnd2934271:0 Tim Ole crwdne2934271:0

@timz19546 - if swapping the display made a difference that points to the backlight cable as having a short. Are you near the beach or get sand storms? The grit in the air can over time wear away the display backlight cable insulation which then creates a short.

crwdns2934271:0Dzi 7, 2025crwdnd2934271:0 Dan crwdne2934271:0

While I’m no where near a beach, but I do have multiple cats and dogs in house and on bed, I do have many fur hair inside my keyboard and vent a lot.

If it is the backlight cable issue, is it possible to swap only the cable? That repair place mentioned that it is nearly impossible to replace only the cable, is this true?

crwdns2934271:0Dzi 7, 2025crwdnd2934271:0 Tim Ole crwdne2934271:0

@timz19546 - Male Cats often mark their territory. Could that have happened? Fur is still not good, but that would affect the systems cooling.

At this point you need to inspect things at least pop the bottom cover off. Review this guide MacBook Pro 14" 2021 Lower Case Replacement Apple did make it easy.

As far as the cables in question these cables are not really replaceable. Some techs have patched them if a line or two have been severed and applying a coating to replace the damaged insulation is about the only thing one can do cheaply. But just like a spliced rope it won’t be at the same strength.

crwdns2934271:0Dzi 7, 2025crwdnd2934271:0 Dan crwdne2934271:0

Actually I already removed the display entirely and make it headless, making it easier to use the built in trackpad.

Thank you again, I’ll try to look out for any damages to the cables and see if replacing is possible.

crwdns2934271:0Dzi 7, 2025crwdnd2934271:0 Tim Ole crwdne2934271:0

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Thanks for the reply,

One thing I forgot to include in my description is that the 3rd repair did inspect briefly and found no apparent water damage, and it wasn’t dropped or physically damaged.

But he did swap the entire display assembly from another mbp of same model and found the booting and display works fine, hence leading to suspect of display issue and found the dimmed image using flashlight.

I don’t know if this info changes anything.

Thanks again for your help — Tim Ole
@timz19546 - if swapping the display made a difference that points to the backlight cable as having a short. Are you near the beach or get sand storms? The grit in the air can over time wear away the display backlight cable insulation which then creates a short. — Dan
While I’m no where near a beach, but I do have multiple cats and dogs in house and on bed, I do have many fur hair inside my keyboard and vent a lot.

If it is the backlight cable issue, is it possible to swap only the cable? That repair place mentioned that it is nearly impossible to replace only the cable, is this true? — Tim Ole
@timz19546 - Male Cats often mark their territory. Could that have happened? Fur is still not good, but that would affect the systems cooling.

At this point you need to inspect things at least pop the bottom cover off. Review this guide MacBook Pro 14" 2021 Lower Case Replacement Apple did make it easy.

As far as the cables in question these cables are not really replaceable. Some techs have patched them if a line or two have been severed and applying a coating to replace the damaged insulation is about the only thing one can do cheaply. But just like a spliced rope it won’t be at the same strength. — Dan
Actually I already removed the display entirely and make it headless, making it easier to use the built in trackpad.

Thank you again, I’ll try to look out for any damages to the cables and see if replacing is possible. — Tim Ole

score 0 · Answer 1 · 2025-04-07T04:45:22-07:00

livfe @livfe

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crwdns2931729:0crwdne2931729:0: Dzi 7, 2025

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Seems like a backlight issue. I am not so familiar on the repair process for these models and it maybe another component that has gone wonky as it can be a more common issue of a blown fuse as I have encountered this numerous times on older models, but @danj can likely help out more if I missed something.

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MacBook Pro 14" 2021

14’’ M1 Max MBP reboot loop with black screen

Issue Description

Repair suggestions

Help needed

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