Back up your data if possible
Shut down the MacBook Air
Press and hold the Power button for 10 seconds
Release the Power button
Wait a few seconds
Press the Power button again to turn it on
If needed, reset NVRAM by turning it on and immediately holding Option + Command + P + R for about 20 seconds
If needed, reset the SMC on Intel MacBook Air by shutting down, then holding Shift + Control + Option + Power for 10 seconds, then releasing and turning it on
If you want to erase and reinstall macOS, restart and hold Command + R, then use Disk Utility and Reinstall macOS