iPhone 12 blackout

If you already tried (to no avail) all the steps provided in this support article:--> If your iPhone won't turn on or is frozen - Apple Support, I suggest that you contact Apple Support directly, using this link:--> Get Support, or make an appointment (*) and have your device inspected at an Apple Store or AASP (Apple Authorized Service Provider) among this list:--> Apple – Location Selector. After checking it out, they'll give you all the available options.

Regards

Giulio

(*) You can do it:

• Online:--> Genius Bar Reservation and Apple Support Options - Apple;
• Contacting a local Apple Store or AASP among the list provided above;
• Using the "Apple Store" app, available and downloadable from AppStore.

I don’t know what quickset is; however, I won’t assume anything here.

These are my absolute top proven troubleshooting tips:

Try the following:

▷ Update your iPhone. 📲

If that didn’t help, then try a Hard Reset:

1. Press volume up (quickly)
2. Press volume down (quickly)
3. Press and hold the power button until the Apple logo ( ) appears

If that didn’t work, then click ▶︎ follow these steps to enter Recovery Mode.

If that didn’t work, then get expert service and support at the Genius Bar.

• Call Apple Support at 1-800-APLCARE.
• International Support.
• Contact Apple Support.
• Chat using Messages.