You may have to try the steps ahead of a re-set in this Support article
about how to reset the System Management Controller (SMC) in Mac.
•How to reset the System Management Controller (SMC) on your Mac - Apple Support
There are steps to see if the issue may be resolved before actually
doing the SMC re-set section. Best to go through & try those first.
.-.-.-.-.
.-.-.-.-.
.-.-.-.-.
And also notice that a separate detail ^ for portable computers that
have the battery. ~ Several 'older models with removable battery' have
other instructions than 'later model whose battery isn't user accessible'...
"Resetting the SMC doesn't reset or otherwise change... contents of [NVRAM or PRAM]"
If the problem isn't reduced through trying the above a few times, do include
a full shut-down and then restart. (You could also try Safe mode, to otherwise
test functions, to perhaps flush out gremlins...? One of the kitchen sink ideas.)
• Use safe mode to isolate issues with your Mac - Apple Support
And in general terms, if the unit has issues that cannot be DIY, get expert help:
In any event...
Good luck & happy computing! 🙂