macbook pro glitch on boot screen

dhineshr Said:

"macbook pro glitch on boot screen: [...]After a week I've noticed for a split second, there is a small glitch or something that comes during the boot screen loading. Can anyone identify this issue and help me solve this, please. I've attached the video for reference. Thanks."

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Your Screen is Failing:

From what you have reported, your screen is apparently defective. So, It is time for a new screen.

What to Try: 

• Take a Screenshot on your Mac - Apple Support. See if you still get this error. Open it on another device, seeing if the lines are still there
• Create a New User, seeing if you still get this error.
• Connect an External Monitor.  If you do not have an HDMI port, then use this adapter: Belkin USB-C to HDMI Adapter - Apple

No Success?

Proceed with the replacement...

Use Send-In Service:

Contact Apple Support:

• Contact Us - Choose Locations
• Proceed from there as Necessary

Apple Send-In Service

At the moment, with the Coronavirus Pandemic, many Apple Stores are still closed at the moment. So, Send-In Service may be the only available option for getting this serviced. So, have Apple take this in through Send-In Service. They will send you a box; you would ship it out to Apple; their engineers would look at it; and the would send it back to you.

OR...

Take it to you local AASP (Apple Authorized Service Provider):

1. Go Here: Find Locations - Apple Authorized Reseller
2. Click: Service & Support
3. Enter: your location information
4. See: if there is an AASP nearby
5. Contact: an AASP that shows up, and find out more about the services that they offer to fix the device

Like @TheLittles mentions, the LCD Panel is most likely at fault here, but if this is only a very brief momentary flash on the display, then it may just be an issue with the video buffer which can sometimes occur on some systems during startup & shutdown although it would be unusual to see what looks like the progress bar spread across the display.

Try connecting an external display and enable mirroring to see if the external display shows the same issue. If the external display does not show the issue, then it means the laptop's built-in Display Assembly (specifically the LCD Panel) is bad. It is possible that with mirroring enabled, the built-in Display Assembly may not show the issue. If this is the case, then try booting the laptop in ClamShell mode to see if the external display shows the issue. Clamshell mode requires the laptop is connected to the charger and using a wired USB keyboard and mouse. Immediately after pressing the power button & hearing the startup chime, then close the lid of the display to enable Clamshell Mode.