I can’t reboot my MacBook pro

You do not have to upgrade unless you need to. Here is my idea about upgrading. These are my rules of thumb about upgrading without pain. Taking a few precautions will help keep you from going through your last experience again.

Before You Upgrade macOS

1. Fix any problems before upgrading.
2. Run First Aid in Disk Utility while booted from your Recovery HD.
3. Backup. Make a bootable clone using CarbonCopy Cloner or use TimeMachine.
4. Be sure your startup disk has 18-20GB of free space during the installation.
5. Upgrade third-party software for compatibility. See App Compatibility Table - RoaringApps. If you have mission critical software, then DO NOT upgrade until you know that software is compatible with the version of macOS you are about to install.
6. Disconnect all third-party peripherals.
7. Download the installer which will be in the Applications folder. Quit the installer after it opens, then make a copy of the installer and save it in the Downloads folder. The one in the Applications folder will be deleted after a successful installation.
8. The download is large, anywhere between 5 and 9GBs. It takes time to complete. Be patient.
9. Double-click on the installer in the Applications folder. Click on the start button to begin the installation.

Appears the computer is already in the process of starting up a Network Recovery provided the computer has an Internet connection. If you use Wi-Fi, then you would have been prompted to select and sign in to your Wi-Fi network. Otherwise, you are using Ethernet which connection is automatic.

Please read Writing an effective Apple Support Communities question. We are here to help. We are all users. We are not mind-readers nor clairvoyants. We only know what you write down and tell us. Be specific and thorough. Include your hardware information and installed version of macOS. Try to write clearly. Think about what you want to say before you write it down, then re-read it to see if it makes sense.

FYI: These are user-only forums. This is not Apple Support. if you need to contact Apple Support, then contact product and tech support:  Contacting Apple for support and service including international calling numbers.

These forums only provide help with Apple products. Thank you for your understanding and support.

No target disk present suggests your internal disk has died or is not formatted. Return to the Utility Menu where this should have started. Select Disk Utility from the Utility Menu and properly partition and format the target disk. The partition scheme should be GUID, and the Format type should be Mac OS Extended, (Journaled).