Q: since this update my computer won't shut down?

Force shutdown by holding the power button for 10 seconds then resetting the SMC often cures the problem Reset the System Management Controller (SMC) on your Mac - Apple Support

If you have Wacom tablet software installed, try uninstalling it.

Try running this program and then copy and paste the output in a reply. The program was created by Etresoft, a frequent contributor.  Please use copy and paste as screen shots can be hard to read. On the screen with Options, please open Options and check the bottom 2 boxes before running. Click “Share Report” button in the toolbar, select “Copy to Clipboard” and then paste into a reply. This will show what is running on your computer. No personal information is shown.
  

Etrecheck – System Information