hardware issues / SMC reset: keyboard, trackpad, flickering screen

Question

Macbook Pro, 13" retina Early 2015, macOS Sierra 10.12.6

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I had my laptop's screen replaced a couple of months ago, and I'm wondering if the bugs I'm seeing are symptoms of a faulty repair job? An SMC rest seems to work for a little while, so could it really be a hardware malfunction? And why would I have not seen any symptoms sooner?

Here's the detailed list of bugs I'm experiencing:

• The haptic feedback on my trackpad comes and goes. It's working correctly most of the time though.
• Occasionally the mouse cursor will continue to move itself after I stop pushing it, like it was lagging or something.
• Today, for the first time, the cursor was completely unresponsive. Haptic feedback, however, was still happening.
• After rebooting the OS failed to connect to either the keyboard or trackpad.
• There was a slight flickering/shimmering in the lower right corner of the screen that took about 20 seconds to settle down.
• I performed an SMC reset, and everything was back to normal for a couple of hours. But now the mouse cursor and/or haptic feedback is intermittently coming and going again.

Any suggestions? I'm quite frustrated at the moment, and worried that something worse is coming down the pike...

Answer 1

You have a hardware issue - possibly two - and you should take it in (back) for service.

The two issues: flickering on the screen and trackpad/keyboard issues are most likely coincidental and have nothing to do with each other. Given that you just had it in for service on the screen and it's showing issues, I would've taken it back already.

The SMC reset really has nothing to do with any of this. The SMC is just Apple's name for the what the rest of the industry calls the PMU or Power Management Unit. Resetting it just sets the sensors, counters, watchdogs etc. back to "zero." The SMC just regulates where power goes and how fast to spin fans based on data it gets back from the rest of the system.

The fact that you have intermittent failing haptic feedback, an unresponsive cursor and a failure to connect to either the keyboard/trackpad, indicates there's a hardware issue.

If it appears SMC reset "fixes" your problem for a little while but then it returns, there's a good chance there's a power issue like a faulty component (resistor, capacitor, etc.) but in the end, the item needs to be serviced. Chances are, you'll need a new top case assembly.