Black iPhone screen

If your iPhone is frozen or just show a black screen, try doing a Forced Restart:

1. Press and quickly release Volume Up

2. Press and quickly release Volume Down

3. Press and hold the Side Button, the phone will restart. Release when you see the Apple Logo.

You can find more useful information here:

If your iPhone won't turn on or is frozen - Apple Support

Follow these steps, testing after each step:

• iPhone Screen Not Working.
• Turn iPhone on or off.
• Force Restart iPhone.

If that didn’t work, then I recommend service.

Service Checklist:

• iPhone service pricing.
• Check AppleCare Coverage.
• Get your iPhone ready for service.

Click ▶︎ Start a Service Request. ⚛️

Need more help?

• Chat now or call 1-800-APLCARE.
• International Support.

Click ▶︎ Check Repair Status. 🔧

Forced Restart should work unless the physical buttons on your iPhone are faulty so they cannot be pressed.

But if it still doesn't work, take your iPhone to an authorized Apple repairer and let them check it.

You can find more information here:

Apple Repair and Repair Status Check - Official Apple Support