First, can we get some DDL so we can test things easier on our end for writing and testing the code?

Next part in my mind is a tad...

One other thought I have:
your Flat File Connection Manager screen looks different than Phil Parkin's.  Which version of visual studio are you guys using?
I've seen oddities with SSRS and...

That is odd.  I have not installed 2005 before, but I know with 2008 R2 and higher I've installed and uninstalled using the base media (with no service pack) even...

I think you'd want to have the same installation media.  As you pointed out, using incorrect installation media cannot remove all of the features.

But Microsoft offers all of...

A difference between the OP and Phil Parkin's post that I noticed is that the OP used the code page 65001, and Phil used 1252.

I am wondering a...

This could be a dumb question as I don't know a lot about oracle, but isn't there an ODBC connection for oracle?  If so, couldn't you run the whole thing...

I betcha windows saw the app get changed when you did windows updates so it thought it was a different app (the hash of the file didn't match up).  

Glad I could help.  I knew you could add programs through too, I just personally like having the port instead of the whole program as it feels like I have...

How slow is the query if you run it directly on the server instead of through openquery?
and what if you use a linked server connection and just use the...

Any reason not to set up a file share on a network drive with restricted permissions (IT department and SSRS account for example) that could store the reports and then...

The easy way is to use add/remove programs.  But if that isn't working, I'd download a copy of SQL Express (it is free), and use that to remove the instance.

As a thought - does connecting as hdcvs-lims-sql\ss2016, 49559 work?  I expect that it will.

If so, then it is likely your firewall is blocking connection on port 1434...

When you say the original media files are not present, do you mean the installation files or do you mean the "c:\program files" folder for SQL express got deleted?
If...

I agree with Sue that MS will likely be your best bet.  But I know from talking with their licensing experts that they use the term "expert" loosly.  I talked...