My MacBook pro suffered a problem with its display recently which left me scratching my head looking for a solution to the flickering display. It was pretty much unusable due to flickering horizontal bars scrolling bottom-to-top on the display. They appeared right after booting, even the log screen was affected. They appeared once logged in when no other apps were running, they appeared over stock apps like Safari & Mail. They appeared over non-stick apps I had installed like Chrome.. they were everywhere!
I had to limit the use of my laptop to [very] short doses to avoid the flickering eating away my patience and sending my frustration levels to new heights. It was a case of Googling solutions on my iPad and switching to my MacBook to give it a try, failing then walking away, making a brew, and trying again.
Resetting NVRAM (or PRAM, the reset sequence is the same)
- Shut down your Mac.
- Locate the following keys on the keyboard: Command (⌘), Option, P, and R.
- Turn on your Mac.
- Press and hold the Command-Option-P-R keys immediately after you hear the startup sound.
- Hold these keys until the computer restarts and you hear the startup sound for a second time.
- Release the keys.
The reset sequence fixed the issue with the flickering display on my Macbook Pro.