It's hard to trace specific hardware problems. Fortunately, Apple offers a convinent way to restart the controller of all the system. It's just like in the old times when we have to restart the Windows machine when there is any problem. Here's how you do it:
- Shut down the MAC.
Powersimultaneously for 5 seconds.
- Release all buttons and press
- It should be solved.
Check the official guide if there is any difference.