I'm sorry for the frustration.  

My guess is that at some point an update partially failed.

Can you,

- Go to the Windows Start Menu

- Try ProSeries Basic Edition 2020 -> Tools Repair Updates

- Launch Basic

If that doesn't work, can you

- Open File Explorer

- Navigate to your installation directory (probably c:\BasWin20)

- Navigate into \32bit\logs

- Email proseries.txt to proseries_engineering@intuit.com