Troubleshooting Apple MacBook issues properly.
I am ready to rip my hair out on some of the answers and misinformation being provided by some as of lately when troubleshooting MacBook issues. So I am going to write a comprehensive guide on how to PROPERLY troubleshoot many of these.
Let's start with some of the most common issues.
1. My 2011 17 or 15 inch MacBook Pro has pink lines on the screen and won't boot.
Answers that I am seeing -- It's your LVDS cable --
WRONG! There is a slight chance that it is but not in the way I see most of these issues manifesting. This machine has a known GPU issue. Your LVDS cable really doesn't fail often. I have never seen one fail in the time that I have been fixing these by just sitting there. After being dropped or having the cable corrode from liquid is a different story.
Pink lines, vertical lines or bars, or not booting is usually a dead GPU.
But, but external video works fine.
Yes because the GPU has separate outputs for external and internal display. Plus the GPU outputs signals such as LCD_EN and BKL_PWM so you can have black screen or no backlight and have a perfect image on external. It doesn't matter. Just because one output is working doesn't mean the GPU is good.
But if I bake it it will be fine right?
NO! The die is falling apart. The bumps are separating from the die and the die itself is falling apart. Heat will make it work for a short amount of time.
I have a 2013-2015 MacBook Air. It doesn't turn on when I push the power button but it will turn on and run on battery if I plug in the charger. The genius bar told me I need a new logic board.
Wrong. The Genius bar often is clueless. Your issue is the trackpad or the trackpad cable. I get Air's all the time that have been diagnosed as a bad board. It ends up being the trackpad and the trackpad cable.
My fans on my MacBook are running at 100% all the time.
I need new thermal paste right?
No, Sometimes that can solve it but most likely you have a sensor issue. Run AHT to ASD to find out which one. Probably will be palmrest and you'll need a new trackpad.
I plan on turning this into a guide and updating this post as time goes on but this is what comes to mind. Please please stop with the misinformation.