Big Sur update issue

Then quit the installation. Press and hold down the Power button until the computer shuts down. Wait 30 seconds before restarting. if the installation still does not finish, then try the following:

Internet/Network Recovery of El Capitan or Later on a Clean Disk

     If possible, back up your files before proceeding.

You will need a fast, working Internet connection, preferably, Ethernet. If you must use Wi-Fi, you will be asked to select your network and enter the network password. This procedure will install the current version of macOS that is compatible with your model.

1. Restart the computer. Immediately, at or before the chime, hold down the (Command-Option-R) keys until a globe appears.
2. The Utility Menu will appear in from 5-20 minutes. Be patient.
3. Select Disk Utility and click on the Continue button.
4. When Disk Utility loads select the target drive (out-dented entry w/type and size) from the Device list.
5. Click on the Erase button in Disk Utility's toolbar. A panel will drop down.
6. Set the partition scheme to GUID.
7. Set the Format type to APFS (SSDs, only if installing Mojave or Catalina ) or Mac OS Extended, (Journaled.)
8. Provide a volume name, usually "Macintosh HD."
9. Click on the Apply button, then click on the Done button when it activates.
10. Quit Disk Utility and return to the Utility Menu.
11. Select Install OS X and click on the Continue button.

Does your computer meet the requirements? macOS Big Sur is compatible with these computers - Apple Support. How to upgrade to macOS Big Sur.

How to upgrade to macOS Big Sur

Depends on the hardware. Anywhere from 25 minutes to more than an hour. The installer will give you time remaining.

What is this? Proof you can use your camera?