MacBook Air won't turn on after battery replacement

 The SMC is responsible for managing power on your Mac. Resetting it can resolve certain uncommon issues related to power or thermal management.

Resetting the SMC may be suggested for Intel-based Mac computers as a final step to resolve issues that could be power related:

•Battery isn't charging

•Mac isn't turning on

•Fans are running fast

•Mac laptop computer gets too warm

•Built-in camera isn't working

If your Mac is experiencing one of these issues, follow the steps appropriate for your Mac model:

How to Reset the SMC of your Mac - Apple Support

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