If you are still experiencing the problem, it is highly likely that you are having a hardware problem.Mac keeps restarting over and over? Mac keeps restarting on its own? MacBook Pro keeps restarting at boot? No worry. Then after, login to your computer as this new user. Create a different user account on your Mac by going to System Preferences > Users & Groups.Try uninstalling Firefox to see if that fixes your flicking problem. It seems that, for some users, Firefox may be the culprit.After regularly starting your Mac, does flickering come back? If not, that means that safe mode fixed it. Does flickering still happen? If flickering does not happen, restart your Mac regularly (without pressing any keys). Then you will see the login screen (now you may release the Shift key) and login your Mac.Apple logo will appear (do not release the Shift key yet) Start your Mac and immediately, press and hold the Shift key.You sometimes can use safe mode to identify your issue. On your Mac, go to System Preferences > Energy Saver > and uncheck the option for “Automatic graphics switching” (note that Mac Air models do not have this option, Mac Book Pro models have this option).Start your Mac, and immediately press the Option, Command, P, and Rkeys together for several seconds (around 20 seconds).Click on this Apple KB article to learn more. Different Mac models require different steps to do this. Reset the System Management Controller (SMC).You can do so by opening the App Store on your Mac. Shut down your Mac by going Apple menu >Shutdown.There are several steps you can perform to resolve screen flickering issues on a Mac. Here is what you can do if your Mac screen is flashing or flickering: Screen flickering issue, fixes Mac screen flickering can be caused by different issues.

Macbook pro 3 beeps apple logo