MacBook Air damaged after update
It doesn't seem you're resetting the SMC correctly. Here’s what you do for a MacBook Air:


Shut down your computer
Keep the power cable plugged in.
Press at the same time shiftoptioncontrol (on the left side of the keyboard) and the power button
Let go
Turn your computer back on with the power button.


Let us know how you go. Many of your symptoms are listed in Apple's article on when you might want to try a SMC reset after performing a somewhat long set of other checks first to be sure it's not software or basic settings:


https://support.apple.com/en-us/HT201295