My MacBook doesn’t turn on

Hold the Power Button for 10 seconds or until the computer turns off. Disconnect all external devices including External connect Display.

Start up a Mac with Apple silicon in safe mode

1. On your Mac, choose Apple menu  > Shut Down.
2. After your Mac shuts down, wait 10 seconds.
3. Press and hold the power button on your Mac until the startup options window appears showing available startup disks and Options.
4. Select a startup disk.
5. Press and hold the Shift key, click Continue in Safe Mode, then release the Shift key.

Turn the Brightness up using the F2 key

Also, the version of Big Sur in you profile is showing 11.2 and is out dated. Current version Big Sur is 11.5.1. Suggest doing a Time Machine Backup Before attempting this update. A Time Machine Backup  is very useful and can be used to Revert to Previous Working macOS.

So the computer is on. But the screen is totally black.

Is this a New Problem or an Old problem ? If New Problem - what changes have happened since the problem happened ??

If this is an OldProblem. - what have you done to fix it ??

https://discussions.apple.com/thread/253023269

In you picture I see your mouse pointer. Can you move it?

Welcome and Thank you too :-)