quickbooks pro 2016 wont open .

Install the trial license of Pro 2020 and try open your file on it.

https://quickbooks.intuit.com/learn-support/en-us/new-subscriptions/download-a-trial-of-quickbooks-d...

It continues to do the same thing.  I have uninstalled and reinstalled.  I have done tool hub repair and none work.  I have installed the trial version of 2020 and tried to open.  It does the same thing.

I appreciate the troubleshooting steps you've performed, therrtl.

Let's try another troubleshooting steps to resolve this. You may consider doing the process with the help of an IT expert. 

We can try repairing or reinstalling Microsoft .NET Framework and repairing Microsoft MSXML. Please check out these articles for the detailed steps for your guide:

• Manually fix Microsoft .NET Framework errors.
• Repair Microsoft MSXML.

After doing the process, start installing QuickBooks Desktop in Selective startup mode. This is to ensure that no other application blocks you from completing the tasks. You may consult with a Windows expert. Let's make sure that before we proceed, we've created a backup of our company file and keep a copy of our QuickBooks Desktop product and license info.

To start your computer in a selective startup mode:

1. Press Windows+R to open the Run command.
2. Type MSConfig and select OK.
3. Select Selective startup and Load system services in the General tab.
4. Go to the Services tab and tick Hide all Microsoft Services box.
5. Click Disable all.
6. Uncheck the Hide all Microsoft services box.
7. Make sure the Windows Installer checkbox is selected from the list of services.
8. Click OK then select Restart.

To complete the process, you can refer to this article then proceed to Step 3 and then, Step 4 in installing and reinstalling QuickBooks in Selective startup.

I'm just a post away if you need more help.

@therrtl 

Did you see any error message?