Correct way to show that software is connected to an instrument?

Let me start by saying that I am a software developer, not a ui/ux designer at all, but in my company I need to cover this role too.

I am developing a desktop software that manages some particular hardware devices.
It is possible to connect these devices to the PC and to start a "real-time connection" with the instrument. While this connection is alive, more functionalities are available.

The main buttons of my software have icons, and the icon for the "Connect" button is a red circle, which (in my mind) reminds of the "REC" button of cameras:

Then, on my main window I need to show somehow that a real-time connection is alive. And I did it by placing a blinking red circle in my window corner:

One of the beta tester (one out of a dozen, more or less), however, reported that

The connect button is always red! So I think there is something wrong with my connection

My question is: since only one beta tester reported that interpretation, should I ignore that or my icon is really wrong? If so, what can I do to improve it?

Edit: I know that red has a precise meaning, but in this case it mimics an existing item, i.e. the REC button on cameras and recorders.
Plus, in this case, wouldn't a plain white circle be meaningless or meadleading?