Pre-test as Web Object... looking for advice/suggestions

I'm looking for advice/suggestions.

I have a course for which we want to track both pre-test and post-test scores.  The course is hosted on Articulate Online.  I published the pre-test as a standalone to AO and inserted it as a web object into Presenter.   (We do not need to track pre-test scores individually but want to get an overall baseline of knowledge to use as a comparison with the post-test results.)  The pre-test web object is set to open within the slide at full screen and not as a separate window.  It is currently set to "close" when finish, instead of directing to a url (since no url is needed).

Here's my problem.  While QA'ing the course, I've gotten feedback that once the learner clicks "finish" the quiz - the browser message appears indicating that the browser is trying to close and instructing the learner to close the browser.  Of course when they do that, it closes the course.

I've now removed the word "finish" from the pass/fail screen but the button still appears (just with no words).  I can change the color of the button so it doesn't stick out like a sore thumb, but then it changes the button color for all buttons which includes the submit button.  I've added instructions to the pass/fail screen telling the learner to "click the forward button" below but now the blank finish button is between my instructions and the player contols.  (But you know not all learners will actually read the instructions.)

I'm concerned that if I change the web object setting to open in a new window, it'll get pop up blocked.  I plan on adding a picture of the player controls to the pass/fail screen so supplement the instructions.  I thought about switching and having the post-test as the web object instead, but then I can't track "passing" individually and then the learner may not get the proper continuing ed credits.

Is there any other way to disable the quiz "finish" button that I haven't found?  Or are there any other suggestions on what I can do to clarify NOT to close the browser but just go to the next slide?  Or have I thought about this all wrong and do you have any other suggestions on how to accomplish having my cake and eating it too?

Thanks for your help.