If the spots are still there, Hardware.
ALT menu allows it to conclude that a failure.
For example, I have a gray spot on the screen of my iMac or my MacBook. I reset SMC and ZAPPRAM, I start on the menu ALT and the task is still there?
Are what we can conclude that a hardware failure.
Another example, on a MacBook, the latest generation, clicking the track pad does not work. SMC ZAPPRAM, starting ALT and click does not work.
Are what we can conclude that a hardware failure.

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