My iPhone 15 bricked after an update, some sort of boot loop, connecting it to mac didn’t work, the phone simply wouldn’t show up. In the end I received a completely new phone, the technician at Apple ...

Recovery mode allows you to update or restore your iPhone using a computer with iTunes or Finder. Here's how to access it.

If your iPhone is showing a black screen that never goes away, you should try resetting it or putting it into recovery mode.