screen problem

There are a few 'resets' that may help or at least provide a break

for troubleshooting (or perhaps comic relief?) One is NVRAM.

Try first: Four keys held on restart; release keys after Mac chime 3x.

"Shut down your Mac, then turn it on and immediately press and

hold these four keys together: Option, Command, P, and R."

..another is SMC. Has other reset details in article.

And there may be hardware issue behind this, not sure if the

built-in diagnostic could help. You may need to seek genius

staff by appointment at Apple store or service provider.