It sounds like your MacBook Pro is experiencing an issue with its software or hardware that's causing it to fail to restart properly. Here are a few steps you can take to troubleshoot the problem:
1. Try resetting the System Management Controller (SMC) on your MacBook Pro.
2. If resetting the SMC doesn't work, try starting your MacBook Pro in Safe Mode.
3. If Safe Mode doesn't work, try running Apple Diagnostics or Apple Hardware Test to check for any hardware issues.
4. If none of these steps resolve the issue, it may be necessary to reinstall macOS on your MacBook Pro. Make sure to back up your data before attempting this.
I hope these steps help you resolve the issue with your MacBook Pro and allow you to update it. If the issue persists, it may be best to take it to an authorized Apple service provider for further diagnosis and repair.