One hour is too long. It usually takes about a maximum of 5 minutes, usually less.
First, try a forced restart:
1. Press Quickly Volume Up
2. Press Quickly Volume Down
3. Press and hold the Power Button until the phone restarts
If your iPhone starts up with the "Hello" screen, then you are good to go.
If your iPhone does NOT boot up, connect it to a PC or Mac, put the phone in Recovery Mode, and do a Restore.
How to make a Restore from PC/Mac:
On your computer. If you use a PC, download the latest version of iTunes. It can be downloaded from the Microsoft Store.
If you are using Mac then you can just get started.
1) Connect your iPhone to your PC / Mac
2) Again, Quickly press Volume Up, then quickly press Volume Down, and this time hold down the Power Button, and keep hold until your iPhone restarts and starts up in Recovery Mode.
Recovery Mode is a black screen, with a computer and cable icon.
On your computer. Now you can select Update or Restore. Update is trying to update your device. Restore deletes EVERYTHING and restores your device to factory settings. Select Restore.