MAC doesn’t start after updates

First, just connecting the ethernet cable should create the best internet connection without any additional steps or effort on your part.

Second, hold in the power button until you are sure everything is off. Disconnect the power cord if necessary.

Intel Macs: Use macOS Recovery on an Intel-based Mac - Apple Support

Silicone Macs (M1 and M2 Macs):

1. On your Mac, choose Apple menu  > Shut Down.
2. Wait for your Mac to shut down completely. A Mac is completely shut down when the screen is black and any lights (including in the Touch Bar) are off.
3. Press and hold the power button on your Mac until the system volume and the Options button appear.
4. Click the Options button, then click Continue. 
5. If asked, select a volume to recover, then click Next.
6. Select an administrator account, then click Next.
7. Enter the password for the administrator account, then click Continue.
8. When the Recovery app appears in the menu bar, you can choose any of the available options in the window or the menu bar.