Macbook pro stuck at boot screen with apple logo and 100 percent progress bar.

Please try the following, in order. Stop at the step where the issue is resolved:

1. Reset your Mac's SMC.
   • Reset the System Management Controller (SMC) on your Mac - Apple Support
   • Fans, keyboard backlight, status indicator, battery indicator, display backlight, power button, close/open the lid, sleep or shut down, battery doesn't charge, MagSafe indicator light incorrect status.
   • Hold down the <shift><control><option> keys, and then, press the power button. Hold all of them for, at least, 10 seconds.
2. Reset your Mac's NVRAM.
   • How to reset NVRAM on your Mac - Apple Support
   • Resets sound volume, display resolution, startup-disk selection, time zone, & kernel panic information.
   • <option><command><P><R>
3. Boot up your Mac in Safe Mode.
   • Try safe mode if your Mac doesn't finish starting up - Apple Support
   • Use safe mode to isolate issues with your Mac - Apple Support
4. Boot up your Mac in Recovery or Internet Recovery Mode.
   • About macOS Recovery - Apple Support
   • When at the initial Recovery Mode screen, select the Disk Utility option.
   • Run Disk Utility > First Aid to verify the startup disk's integrity.
5. Boot up your Mac in Single-User Mode.
   • How to start up your Mac in single-user or verbose mode - Apple Support
   • At the command prompt, type: /sbin/fsck -fy <return>

     If fsck makes any repairs, you will get a message that says: Files System was modified. If you do, run fsck again until the "The volume <volumename> appears to be OK."

   • Type reboot at the prompt to exit Single-User Mode.
6. Run either Apple Hardware Test (AHT) (pre-2013 Macs) or Apple Diagnostics (2013+ Macs) to uncover any hardware issues with your Mac.
   • Use Apple Diagnostics or Apple Hardware Test - Apple Support
   • About the "Apple Hardware Test does not support this machine" message - Apple Support
   • How to Use Apple Hardware Test to Diagnose Mac Problems - OSXDaily
7. Make a Genius Bar appointment at your local Apple Store.
   • Check Your Service and Support Coverage - Apple Support
   • For getting the right support, here's a genius idea - Apple
   • To contact Apple Support directly.

Same thing happened to me. Every one of the aforementioned "fixes" did not fix anything.

A genius from a Genius Bar at an Apple Store determined that the GPU was fried and the logic board may have needed replacing too. I was also given the bad news that Apple no longer services or carries parts for an older (my) model (15-inch, Early 2011 MacBook Pro) for logic board issues and that if they did, it would probably cost around $500 to fix.

After searching the internet for days, I found a company in Alabama that does logic board repairs very reasonably. They determined that the GPU was bad and when replaced the logic board worked fine after testing. It cost me $429 (with the $89/UPS Next Day Air shipping option).

I'm happy to say that my MBP is back and working nicely as my two-fold functioning Master in a Master/Slave set-up in my music studio as well as being my portable studio for external writing/recording sessions. Also need it because it has the internal DVD drive along with 16 GB memory and a 1TB HD... hard to find THAT for $500 (in good condition)!

Sorry to bring a dark cloud to the picnic but it's good for you to know...

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