My MacBook Air 2020 won’t turn on new power supply but still will not turn on

Hi,

If your MacBook Air has Intel processor, resetting SMC could solve your issue.

Reset the SMC of your Mac - Apple Support

If CPU is Apple Silicon, restart your MacBook Air and see if it start up.

if they don't help, you'd better take your MacBook Air to your local retail AppleStore, Genius Bar or Apple Authorized Service Provider to be examined your MacBook Air there.

Genius Bar Reservation and Apple Support Options - Apple

Find Locations

If your Mac doesn't turn on - Apple Support describes what you need to do. Follow each of those steps all the way through and including Step 7.