It happened 2 updates ago... My screen will look pixelated, flicker, turn blue and sometimes black but it will never recover in that session. Sometimes, when I restart it, it will actually work for a little while, but basically it has become a brick. Please help! I have run the diagnostic program and there's nothing wrong with it... supposedly.
Welcome.
I suspect you've already tried this but I would suggest resetting the NVRAM and SMC first.
Next, try booting into Safe Mode to see if the issue persists there for a little while.
The model # you gave spans a few generations ('13-'15) and may or may not have dual graphics cards but if your machine does in fact have a discrete graphics processor (i.e., GPU), you may try turning off the Integrated graphics and see if the issue persists. --this may tell you if it's related to the graphics processor or not depending on whether the issue pops-up again.
If that does not resolve the issue, the issue may require further testing and diagnostics on the hardware. The built-in diagnostic program will identify most hardware issues but your machine may require a bench technician for further tests and diagnostics (e.g., Apple Service Diagnostic).
Macbook Pro 15" (A1398) Screen Flickers, Blacks and Blues... Shuts down
