how to factory reset a phone that wont turn on

Hi chloeeeee_hhjffz12,

Welcome to Apple Support Communities. We understand that you're having an issue with your iPhone powering on. We'd like to help.

Let's have you start with these steps to try to force your iPhone to turn back on:

If your screen is black or frozen

Follow the steps for your device.

On your iPhone 8 or later, including iPhone SE (2nd and 3rd generation)

1. Press and quickly release the volume up button.

2. Press and quickly release the volume down button.

3. Press and hold the side button until you see the Apple logo.

4. If your phone doesn't turn on, follow these steps to check your hardware and charge your phone. You might need to charge for up to an hour.

5. If your phone still doesn't turn on, contact Apple Support.

If you're unable to power on your iPhone this way, it may need service. You can connect with Apple Support to work on finding the best option for you if that happens.

Hope that helps!

There are only two possible results when you use the Forced Restart mentioned above.

1) The phone returns to normal operation...or...

2) The phone has a hardware problem that will need attention at the Apple Store or authorized Apple Service shop